Category Archives: Cosmology and Extragalactic Astrophysics

Low-redshift estimates of the absolute scale of baryon acoustic oscillations [CEA]

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http://arxiv.org/abs/2303.15066


Measurements of the characteristic length scale $r_s$ of the baryon acoustic oscillations (BAO) provide a robust determination of the distance-redshift relation. Currently, the best (sub-per cent) estimate of $r_s$ at the drag epoch is provided by Cosmic Microwave Background (CMB) observations assuming the validity of the standard $\Lambda$CDM model at $z \sim 1000$. Therefore, inferring $r_s$ from low-$z$ observations in a model-independent way and comparing its value with CMB estimates provides a consistency test of the standard cosmology and its assumptions at high-$z$. In this paper, we address this question and estimate the absolute BAO scale combining angular BAO measurements and type Ia Supernovae data. Our analysis uses two different methods to connect these data sets and finds a good agreement between the low-$z$ estimates of $r_{s}$ with the CMB sound horizon at drag epoch, regardless of the value of the Hubble constant $H_0$ considered. These results highlight the robustness of the standard cosmology at the same time that they also reinforce the need for more precise cosmological observations at low-$z$.

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T. Lemos, R. Ruchika, J. Carvalho, et. al.
Tue, 28 Mar 23
32/81

Comments: 8 pages, 4 tables, and 3 figures

Constraints on cosmic curvature from cosmic chronometer and quasar observations [CEA]

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http://arxiv.org/abs/2303.15401


We consider cosmic chronometer (CC) data for the Hubble parameter, quasar (QSO) luminosities data of X-rays and ultraviolet rays emission, and the latest measurements of the present value of the Hubble parameter from 2018 Planck mission (PL18), and SH0ES observations (SHOES) to constrain the present value of cosmic curvature density parameter. We consider three kinds of dark energy models: the $\Lambda$CDM model, the wCDM model, and the CPL parametrization. In all these three models, we find higher values of the matter-energy density parameter, $\Omega_{\rm m0}$ compared to the one obtained from the Planck 2018 mission of CMB observation. Also, we find evidence for a nonflat and closed Universe at 0.5$\sigma$ to 3$\sigma$ confidence levels. The flat Universe is almost 2 to 3$\sigma$, 1 to 1.5$\sigma$, and 0.5 to 1$\sigma$ away from the corresponding mean values, obtained in $\Lambda$CDM model, wCDM model, and CPL parametrization respectively obtained from different combinations of datasets. The evidence for nonzero cosmic curvature is lesser in dynamical dark energy models compared to the $\Lambda$CDM model. That means the evidence of nonzero cosmic curvature depends on the behavior of the equation of state of the dark energy. Since the values of the cosmic curvature are degenerate to the equation of state of the dark energy, we also consider a model independent analysis to constrain the cosmic curvature using the combination of Gaussian process regression analysis and artificial neural networks analysis. In the model independent analysis, we also find evidence for a closed Universe, and the flat Universe is almost 1$\sigma$ away. So, both the model dependent and independent analyses favor a closed Universe from the combinations of CC, QSO, and $H_0$ observations.

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B. Dinda
Tue, 28 Mar 23
34/81

Comments: 17 pages (double column), 7 figures, 6 tables, comments are welcome

Constraint on Early Dark Energy from Isotropic Cosmic Birefringence [CEA]

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http://arxiv.org/abs/2303.15369


Polarization of the cosmic microwave background (CMB) is sensitive to new physics violating parity symmetry, such as the presence of a pseudoscalar “axionlike” field. Such a field may be responsible for early dark energy (EDE), which is active prior to recombination and provides a solution to the so-called Hubble tension. The EDE field coupled to photons in a parity-violating manner would rotate the plane of linear polarization of the CMB and produce a cross-correlation power spectrum of $E$- and $B$-mode polarization fields with opposite parities. In this paper, we fit the $EB$ power spectrum predicted by the photon-axion coupling of the EDE model with a potential $V(\phi)\propto [1-\cos(\phi/f)]^3$ to polarization data from Planck. We find that the unique shape of the predicted $EB$ power spectrum is not favored by the data and obtain a first constraint on the photon-axion coupling constant, $g=(0.04\pm 0.16)M_{\text{Pl}}^{-1}$ (68% CL), for the EDE model that best fits the CMB and galaxy clustering data. This constraint is independent of the miscalibration of polarization angles of the instrument or the polarized Galactic foreground emission. Our limit on $g$ may have important implications for embedding EDE in fundamental physics, such as string theory.

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J. Eskilt, L. Herold, E. Komatsu, et. al.
Tue, 28 Mar 23
47/81

Comments: 7 pages, 3 figures, 1 table. The stacked EB power spectrum is publicly available at this https URL

Geometric Methods for Spherical Data, with Applications to Cosmology [CEA]

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http://arxiv.org/abs/2303.15278


This survey is devoted to recent developments in the statistical analysis of spherical data, with a view to applications in Cosmology. We will start from a brief discussion of Cosmological questions and motivations, arguing that most Cosmological observables are spherical random fields. Then, we will introduce some mathematical background on spherical random fields, including spectral representations and the construction of needlet and wavelet frames. We will then focus on some specific issues, including tools and algorithms for map reconstruction (\textit{i.e.}, separating the different physical components which contribute to the observed field), geometric tools for testing the assumptions of Gaussianity and isotropy, and multiple testing methods to detect contamination in the field due to point sources. Although these tools are introduced in the Cosmological context, they can be applied to other situations dealing with spherical data. Finally, we will discuss more recent and challenging issues such as the analysis of polarization data, which can be viewed as realizations of random fields taking values in spin fiber bundles.

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J. Duque and D. Marinucci
Tue, 28 Mar 23
56/81

Comments: 25 pages, 6 figures

Revisiting $f(R,T)$ cosmologies [CEA]

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http://arxiv.org/abs/2303.15208


We review the status of $f(R,T)$ theories, where $T$ is the trace of the energy momentum tensor $T^{\mu\nu}$, concerning the evolution of the cosmological flat Friedmann-Lema\^itre-Robertson-Walker (FLRW) background expansion. We start focusing on the modified Friedmann equations for the case of a minimally coupled gravitational Lagrangian of the type $f(R,T)=R +\alpha e^{\beta T} + \gamma_{n} T^{n}$. With this choice one is allowed to cover all existing proposals in the literature via four free parameters and all relevant $f(R,T)$ models as well as the $\Lambda$CDM model can be achieved in the appropriate limit. We show that in such minimally coupled case there exists a useful constraining relation between the effective fractionary total matter density with arbitrary equation of state parameter and the modified gravity parameters. Then, with this association the modified gravity sector can be independently constrained using estimations of the gas mass fraction in galaxy clusters. Using cosmological background data and demanding the universe is old enough to accommodate the existence of Galactic globular clusters with estimated age of at least $\sim 13$ Gyrs we find a narrow range of the modified gravity free parameter space in which this class of theories remains cosmologically viable. As expected, this preferred parameter space region accommodates the $\Lambda$CDM limit of $f(R,T)$ models. We also work out the non-minimally coupled case in the metric-affine formalism and find that there are no viable cosmologies in the latter situation.

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A. Jeakel, J. Silva and H. Velten
Tue, 28 Mar 23
63/81

Comments: 9 pages, 4 figures

Measuring the speed of light with updated Hubble diagram of high-redshift standard candles [CEA]

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http://arxiv.org/abs/2303.14674


The possible time variation of the fundamental constants of nature has been an active subject of research in modern physics. In this paper, we propose a new method to investigate such possible time variation of the speed of light $c$ using the updated Hubble diagram of high-redshift standard candles including Type Ia Supernovae (SNe Ia) and high-redshift quasars (based on UV-X relation). Our findings show that the SNe Ia Pantheon sample, combined with currently available sample of cosmic chronometers, would produce robust constraints on the speed of light at the level of $c/c_0=1.03\pm0.03$. For the Hubble diagram of UV+X ray quasars acting as a new type of standard candles, we obtain $c/c_0=1.19\pm0.07$. Therefore, our results confirm that there is no strong evidence for the deviation from the constant speed of light up to $z\sim 2$. Moreover, we discuss how our technique might be improved at much higher redshifts ($z\sim5$), focusing on future measurements of the acceleration parameter $X(z)$ with gravitational waves (GWs) from binary neutron star mergers. In particular, in the framework of the second-generation space-based GW detector, DECi-hertz Interferometer Gravitational-wave Observatory (DECIGO), the speed of light is expected to be constrained with the precision of $\Delta{c}/c=10^{-3}$.

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Y. Liu, S. Cao, M. Biesiada, et. al.
Tue, 28 Mar 23
72/81

Comments: 11 pages,8 figures, accepted by ApJ

Non-Gaussianity in rapid-turn multi-field inflation [CEA]

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http://arxiv.org/abs/2303.14156


We show that theories of inflation with multiple, rapidly turning fields can generate large amounts of non-Gaussianity. We consider a general theory with two fields, an arbitrary field-space metric, and a potential that supports sustained, rapidly turning field trajectories. Our analysis accounts for non-zero field cross-correlation and does not fix the power spectra of curvature and isocurvature perturbations to be equal at horizon crossing. Using the $\delta N$ formalism, we derive a novel, analytical formula for bispectrum generated from multi-field mixing on super-horizon scales. Rapid-turn inflation can produce a bispectrum with several potentially large contributions that are not necessarily of the local shape. We exemplify the applicability of our formula with a fully explicit model and show that the new contributions indeed can generate a large amplitude of local non-Gaussianity, $f_{\rm NL}^{\rm loc}\sim {\cal O}(1)$. These results will be important when interpreting the outcomes of future observations.

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O. Iarygina, M. Marsh and G. Salinas
Mon, 27 Mar 23
28/59

Comments: 35 pages, 6 figures

Physics-informed neural networks in the recreation of hydrodynamic simulations from dark matter [CEA]

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http://arxiv.org/abs/2303.14090


Physics-informed neural networks have emerged as a coherent framework for building predictive models that combine statistical patterns with domain knowledge. The underlying notion is to enrich the optimization loss function with known relationships to constrain the space of possible solutions. Hydrodynamic simulations are a core constituent of modern cosmology, while the required computations are both expensive and time-consuming. At the same time, the comparatively fast simulation of dark matter requires fewer resources, which has led to the emergence of machine learning algorithms for baryon inpainting as an active area of research; here, recreating the scatter found in hydrodynamic simulations is an ongoing challenge. This paper presents the first application of physics-informed neural networks to baryon inpainting by combining advances in neural network architectures with physical constraints, injecting theory on baryon conversion efficiency into the model loss function. We also introduce a punitive prediction comparison based on the Kullback-Leibler divergence, which enforces scatter reproduction. By simultaneously extracting the complete set of baryonic properties for the Simba suite of cosmological simulations, our results demonstrate improved accuracy of baryonic predictions based on dark matter halo properties, successful recovery of the fundamental metallicity relation, and retrieve scatter that traces the target simulation’s distribution.

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Z. Dai, B. Moews, R. Vilalta, et. al.
Mon, 27 Mar 23
31/59

Comments: N/A

APES: Approximate Posterior Ensemble Sampler [CEA]

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http://arxiv.org/abs/2303.13667


This paper proposes a novel approach to generate samples from target distributions that are difficult to sample from using Markov Chain Monte Carlo (MCMC) methods. Traditional MCMC algorithms often face slow convergence due to the difficulty in finding proposals that suit the problem at hand. To address this issue, the paper introduces the Approximate Posterior Ensemble Sampler (APES) algorithm, which employs kernel density estimation and radial basis interpolation to create an adaptive proposal, leading to fast convergence of the chains. The APES algorithm’s scalability to higher dimensions makes it a practical solution for complex problems. The proposed method generates an approximate posterior probability that closely approximates the desired distribution and is easy to sample from, resulting in smaller autocorrelation times and a higher probability of acceptance by the chain. In this work, we compare the performance of the APES algorithm with the affine invariance ensemble sampler with the stretch move in various contexts, demonstrating the efficiency of the proposed method. For instance, on the Rosenbrock function, the APES presented an autocorrelation time 140 times smaller than the affine invariance ensemble sampler. The comparison showcases the effectiveness of the APES algorithm in generating samples from challenging distributions. This paper presents a practical solution to generating samples from complex distributions while addressing the challenge of finding suitable proposals. With new cosmological surveys set to deal with many new systematics, which will require many new nuisance parameters in the models, this method offers a practical solution for the upcoming era of cosmological analyses.

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S. Vitenti and E. Barroso
Mon, 27 Mar 23
33/59

Comments: 15 pages, 6 figures, 7 tables

Primordial feature constraints from BOSS+eBOSS [CEA]

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http://arxiv.org/abs/2303.13946


Understanding the universe in its pristine epoch is crucial in order to obtain a concise comprehension of the late-time universe. Although current data in cosmology are compatible with Gaussian primordial perturbations whose power spectrum follows a nearly scale-invariant power law, this need not be the case when a fundamental theoretical construction is assumed. These extended models lead to sharp features in the primordial power spectrum, breaking its scale invariance. In this work, we obtain combined constraints on four primordial feature models by using the final data release of the BOSS galaxies and eBOSS quasars. By pushing towards the fundamental mode of these surveys and using the larger eBOSS volume, we were able to extend the feature parameter space (i.e. the feature frequency $\omega$) by a factor of four compared to previous analyses using BOSS. While we did not detect any significant features, we show that next-generation galaxy surveys such as DESI will improve the sensitivity to features by a factor of 7, and will also extend the parameter space by a factor of 2.5.

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T. Mergulhão, F. Beutler and J. Peacock
Mon, 27 Mar 23
50/59

Comments: 28 + 4 pages, 16 figures

Impact of symmetron screening on the Hubble tension: new constraints using cosmic distance ladder data [CEA]

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http://arxiv.org/abs/2303.12827


Fifth forces are ubiquitous in modified theories of gravity. To be compatible with observations, such a force must be screened on solar-system scales but may still give a significant contribution on galactic scales. If this is the case, the fifth force can influence the calibration of the cosmic distance ladder, hence changing the inferred value of the Hubble constant $H_0$. In this paper, we analyze symmetron screening and show that it generally increases the Hubble tension. On the other hand, by doing a full statistical analysis, we show that cosmic distance ladder data are able to constrain the theory to a level competitive with solar-system tests — currently the most constraining tests of the theory. For the standard coupling case, the constraint on the symmetron Compton wavelength is $\lambda_{\rm C} \lesssim 2.5 \, \mathrm{Mpc}$. Thus, distance ladder data constitutes a novel and powerful way of testing this, and similar, types of theories.

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M. Högås and E. Mörtsell
Fri, 24 Mar 23
2/56

Comments: 11 pages, 9 figures. Comments are welcome

A flashing beacon in axion inflation: recurring bursts of gravitational waves in the strong backreaction regime [CEA]

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http://arxiv.org/abs/2303.13425


The coupling between a pseudo-scalar inflaton and a gauge field leads to an amount of additional density perturbations and gravitational waves (GWs) that is strongly sensitive to the inflaton speed. This naturally results in enhanced GWs at (relatively) small scales that exited the horizon well after the CMB ones, and that can be probed by a variety of GW observatories (from pulsar timing arrays, to astrometry, to space-borne and ground-based interferometers). This production occurs in a regime in which the gauge field significantly backreacts on the inflaton motion. Contrary to earlier assumptions, it has been recently shown that this regime is characterized by an oscillatory behavior of the inflaton speed, with a period of~${\rm O } \left( 5 \right)$ e-folds. Bursts of GWs are produced at the maxima of the speed, imprinting nearly periodic bumps in the frequency-dependent spectrum of GWs produced during inflation. This can potentially generate correlated peaks appearing in the same or in different GWs experiments.

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J. Garcia-Bellido, A. Papageorgiou, M. Peloso, et. al.
Fri, 24 Mar 23
6/56

Comments: 32 pages, 6 figures, link to an animation of the results: this https URL

A test of invariance of dark matter halo surface density using multiwavelength mock galaxy catalogues [CEA]

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http://arxiv.org/abs/2303.12859


A large number of observations have shown that the dark matter halo surface density, given by the product of halo core radius and core density is nearly constant for a diverse suite of galaxies. Although this invariance of the halo surface density is violated at galaxy cluster and group scales, it is still an open question on whether the aforementioned constancy on galactic scales can be explained within $\Lambda$CDM. For this purpose, we probe the variation of halo surface density as a function of mass using multi-wavelength mock galaxy catalogs from $\Lambda$CDM simulations, where the adiabatic contraction of dark matter halos in the presence of baryons has been taken into account. We find that these baryonified $\Lambda$CDM halos were best fitted with a generalized-NFW profile, and the halo surface density from these halos has a degeneracy with respect to both the halo mass and the virial concentration. We find that the correlation with mass when averaged over concentration is consistent with a constant halo surface density. However, a power-law dependence as a function of halo mass also cannot be ruled out.

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G. K., S. Desai and A. Paranjape
Fri, 24 Mar 23
18/56

Comments: 10 pages, 11 figures

How to detect lensing rotation [CEA]

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http://arxiv.org/abs/2303.13313


Gravitational lensing rotation of images is predicted to be negligible at linear order in density perturbations, but can be produced by the post-Born lens-lens coupling at second order. This rotation is somewhat enhanced for Cosmic Microwave Background (CMB) lensing due to the large source path length, but remains small and very challenging to detect directly by CMB lensing reconstruction alone. We show the rotation may be detectable at high significance as a cross-correlation signal between the curl reconstructed with Simons Observatory (SO) or CMB-S4 data, and a template constructed from quadratic combinations of large-scale structure (LSS) tracers. Equivalently, the lensing rotation-tracer-tracer bispectrum can also be detected, where LSS tracers considered include the CMB lensing convergence, galaxy density, and the Cosmic Infrared Background (CIB), or optimal combinations thereof. We forecast that an optimal combination of these tracers can probe post-Born rotation at the level of $5.7\sigma$-$6.1\sigma$ with SO and $13.6\sigma$-$14.7\sigma$ for CMB-S4, depending on whether standard quadratic estimators or maximum a posteriori iterative methods are deployed. We also show possible improvement up to $21.3\sigma$ using a CMB-S4 deep patch observation with polarization-only iterative lensing reconstruction. However, these cross-correlation signals have non-zero bias because the rotation template is quadratic in the tracers, and exists even if the lensing is rotation free. We estimate this bias analytically, and test it using simple null-hypothesis simulations to confirm that the bias remains subdominant to the rotation signal of interest. Detection and then measurement of the lensing rotation cross-spectrum is therefore a realistic target for future observations.

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M. Robertson and A. Lewis
Fri, 24 Mar 23
39/56

Comments: 17 pages, 13 figures, 4 tables

Predicting the Initial Conditions of the Universe using Deep Learning [CEA]

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http://arxiv.org/abs/2303.13056


Finding the initial conditions that led to the current state of the universe is challenging because it involves searching over a vast input space of initial conditions, along with modeling their evolution via tools such as N-body simulations which are computationally expensive. Deep learning has emerged as an alternate modeling tool that can learn the mapping between the linear input of an N-body simulation and the final nonlinear displacements at redshift zero, which can significantly accelerate the forward modeling. However, this does not help reduce the search space for initial conditions. In this paper, we demonstrate for the first time that a deep learning model can be trained for the reverse mapping. We train a V-Net based convolutional neural network, which outputs the linear displacement of an N-body system, given the current time nonlinear displacement and the cosmological parameters of the system. We demonstrate that this neural network accurately recovers the initial linear displacement field over a wide range of scales ($<1$-$2\%$ error up to nearly $k = 1\ \mathrm{Mpc}^{-1}\,h$), despite the ill-defined nature of the inverse problem at smaller scales. Specifically, smaller scales are dominated by nonlinear effects which makes the backward dynamics much more susceptible to numerical and computational errors leading to highly divergent backward trajectories and a one-to-many backward mapping. The results of our method motivate that neural network based models can act as good approximators of the initial linear states and their predictions can serve as good starting points for sampling-based methods to infer the initial states of the universe.

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V. Jindal, D. Jamieson, A. Liang, et. al.
Fri, 24 Mar 23
52/56

Comments: N/A

Fast and accurate collapse-time predictions for collisionless matter [CEA]

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http://arxiv.org/abs/2303.12832


We consider the gravitational collapse of collisionless matter seeded by three crossed sine waves with various amplitudes, also in the presence of a linear external tidal field. We explore two theoretical methods that are more efficient than standard Lagrangian perturbation theory (LPT) for resolving shell-crossings, the crossing of particle trajectories. One of the methods completes the truncated LPT series for the displacement field far into the UV regime, thereby exponentially accelerating its convergence while at the same time removing pathological behavior of LPT observed in void regions. The other method exploits normal-form techniques known from catastrophe theory, which amounts here to replacing the sine-wave initial data by its second-order Taylor expansion in space at shell-crossing location. This replacement leads to a speed-up in determining the displacement field by several orders of magnitudes, while still achieving permille-level accuracy in the prediction of the shell-crossing time. The two methods can be used independently, but the overall best performance is achieved when combining them. Lastly, we find accurate formulas for the nonlinear density and for the triaxial evolution of the fluid in the fundamental coordinate system, as well as report a newly established exact correspondence between perfectly symmetric sine-wave collapse and spherical collapse.

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C. Rampf, S. Saga, A. Taruya, et. al.
Fri, 24 Mar 23
54/56

Comments: 30 pages, 24 figures, submitted at PRD

Resonant neutrino self-interactions and the $H_0$ tension [CEA]

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http://arxiv.org/abs/2303.12792


In this work, we study the previously unexplored resonant region of neutrino self-interactions. Current disagreement on late and early time observations of the Universe expansion could be solved with new physics acting before the recombination era. Nonstandard neutrino self-interactions are among the most appealing candidates to solve this issue since they could be testable in the near (or middle) future. We use linear cosmological datasets to test neutrino self-interactions for a sample of fixed scalar mediator masses in the range $10^{-2}$ eV $\leq m_{\varphi}\leq 10^{2}$ eV. The resonant behavior produces observable effects at lower couplings than those reported in the literature for heavy and light mediators. We observe that in the best case scenario, using the Planck + BAO dataset, the tension with local measurements of $H_0$ eases from 4.9$\sigma$ (for $\Lambda$CDM) down to 2.8$\sigma$. The joint data set which includes Planck, BAO, and $H_0$ prefers a non-zero interaction with at least 2.3$\sigma$ significance in the range $0.5$ eV $\leq m_{\varphi}\leq 10$ eV. These results add the last piece in the parameter space of neutrino self-interactions at the linear perturbation regime.

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J. Venzor, G. Garcia-Arroyo, A. Pérez-Lorenzana, et. al.
Thu, 23 Mar 23
5/67

Comments: N/A

Cosmological studies with VLBI [CEA]

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http://arxiv.org/abs/2303.12676


Current cosmological controversies can be solved if a sufficient level of precision is achieved by observations. Future surveys with the next generation of telescopes will offer significantly improved depth and angular resolution with respect to existing observations, opening the so-called “era of precision cosmology”. But, that era can be considered already started at the radio wavelengths with Very Long Baseline Interferometry (VLBI). In this paper, we give an overview on how VLBI is contributing to some open questions in contemporary cosmology by reaching simultaneously the largest distances and the smallest scales.

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C. Spingola
Thu, 23 Mar 23
14/67

Comments: 14 pages, no figures. To be published in the proceedings of the 15th European VLBI Network Symposium and Users’ Meeting (EVN2022), 11-15 July 2022, University College Cork, Ireland. Based on invited review talk

Do the CMB Temperature Fluctuations Conserve Parity? [CEA]

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http://arxiv.org/abs/2303.12106


Observations of the Cosmic Microwave Background (CMB) have cemented the notion that the large-scale Universe is both statistically homogeneous and isotropic. But is it invariant also under mirror reflections? To probe this we require parity-sensitive statistics: for scalar observables, the simplest is the four-point function. We make the first measurements of the parity-odd CMB trispectrum, focusing on the large-scale ($2<\ell<510$) temperature anisotropies measured by Planck. This is facilitated by new maximum-likelihood estimators for binned correlators, which account for mask convolution and leakage between even- and odd-parity components, and achieve optimal variances within $\approx 20\%$. We perform a blind test for parity violation by comparing a $\chi^2$ statistic from Planck to theoretical expectations, using two suites of simulations to account for the possible likelihood non-Gaussianity and residual foregrounds. We find consistency at the $\approx 0.5\sigma$ level, yielding no evidence for parity violation, with roughly $250\times$ the squared sensitivity of large scale structure measurements (according to mode-counting arguments), and with the advantage of linear physics, Gaussian statistics, and accurate mocks. The measured trispectra can be used to constrain physical models of inflationary parity violation, including Ghost Inflation, Cosmological Collider scenarios, and Chern-Simons gauge fields. Considering eight such models, we find no evidence for new physics, with a maximal detection significance of $2.0\sigma$. These results suggest that the recent parity excesses seen in the BOSS galaxy survey are not primordial in origin. Tighter constraints can be wrought by including smaller scales (though rotational invariance washes out the flat-sky limit) and adding polarization data.

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O. Philcox
Thu, 23 Mar 23
16/67

Comments: 7+12 pages, 4+5 figures, submitted to Phys. Rev. Lett. Code available at this https URL

Constraining f(Q) Cosmology with Standard Sirens [CEA]

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http://arxiv.org/abs/2303.12674


In this dissertation, we study two cosmological models based on $f(Q)$ gravity. We resort to mock catalogs of standard siren (SS) events to see whether data from future gravitational wave (GWs) observatories will be able to distinguish these models from $\Lambda$CDM.
The first model is the most general $f(Q)$ formulation that replicates a $\Lambda$CDM background, with deviations appearing only at the perturbative level. It has one additional free parameter compared to $\Lambda$CDM, $\alpha$, which when set to zero falls back to $\Lambda$CDM. We show that LIGO-Virgo is unable to constrain $\alpha$, due to the high error and low redshift of the measurements, whereas LISA and the ET will, with the ET outperforming LISA. The catalogs for both LISA and LIGO-Virgo show non-negligible statistical fluctuations, where we consider three representative catalogs (the best, median and worst), whereas for the ET, only a single catalog is considered, as the number of events is large enough for statistical fluctuations to be neglected. The best LISA catalog is the one with more low redshift events, while the worst LISA catalog features fewer low redshift events. Additionally, if we are to observe a bad LISA catalog, we can rely on data from LIGO-Virgo to improve the quality of the constrains, bringing it closer to a median LISA catalog.
The second model attempts to replace dark energy by making use of a specific form of the function $f(Q)$. We study this model resorting to dynamical system techniques to show the regions in parameter space with viable cosmologies. Using model selection criteria, we show that no number of SS events is, by itself, able to tell this model and $\Lambda$CDM apart. We then show that if we add current type Ia Supernova (SnIa) data, tensions in this model arise when compared to the constrains set by the SS events.

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J. Ferreira
Thu, 23 Mar 23
33/67

Comments: 58 pages, 25 figures

WIMP cross-section limits from LOFAR observations of dwarf spheroidal galaxies [CEA]

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http://arxiv.org/abs/2303.12155


Weakly interacting massive particles (WIMPs) can self-annihilate and thus provide us with the possibility for an indirect detection of Dark Matter (DM). Dwarf spheroidal (dSph) galaxies are excellent places to search for annihilation signals because they are rich in DM and background emission is low. If magnetic fields in dSph exist, the particles produced in DM annihilation emit synchrotron radiation. We use the non-detection of 150 MHz radio continuum emission from dSph galaxies with the LOw Frequency ARray (LOFAR) to derive constraints on the annihilation cross-section of WIMPs into electron-positron pairs. Our main underlying assumption is that the transport of the CRs can be described by the diffusion approximation which necessitates the existence of magnetic fields. We use observations of six dSph galaxies in the LOFAR Two-metre Sky Survey (LoTSS). The data are re-imaged and a radial profile is generated for each galaxy. We also use stacking to increase the sensitivity. In order to derive upper limits on the WIMP cross-section, we inject fake Gaussian sources into the data which are then detected with 2$\sigma$ significance in the radial profile. These sources represent the lowest emission we would have been able to detect.
We present limits from the observations of individual galaxies as well as from stacking. We explore the uncertainty due to the choice of diffusion and magnetic field parameters by constructing three different model scenarios: optimistic (OPT), intermediate (INT), and pessimistic (PES). Assuming monochromatic annihilation into electron-positron pairs, the limits from the INT scenario exclude thermal WIMPs below 20 GeV and the limits from the OPT scenario even exclude WIMPs below 70 GeV. The INT limits can compete with limits set by Fermi-LAT using $\gamma$-ray observations of multiple dwarf galaxies and they are especially strong for low WIMP masses.

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L. Gajović, F. Welzmüller, V. Heesen, et. al.
Thu, 23 Mar 23
41/67

Comments: 15 pages, 10 figures, to be published in Astronomy & Astrophysics

Impact of the Hubble tension on the $r$-$n_s$ contour [CEA]

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http://arxiv.org/abs/2303.12345


The injection of early dark energy (EDE) before the recombination, a possible resolution of the Hubble tension, will not only shift the scalar spectral index $n_s$ towards $n_s=1$, but also be likely to tighten the current upper limit on tensor-to-scalar ratio $r$. In this work, with the latest CMB datasets (Planck PR4, ACT, SPT and BICEP/Keck), as well as BAO and SN, we confirm this result, and discuss its implication on inflation. We also show that if we happen to live with EDE, how the different inflation models currently allowed would be distinguished by planned CMB observations, such as CMB-S4 and LiteBIRD.

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J. Jiang, G. Ye and Y. Piao
Thu, 23 Mar 23
44/67

Comments: 13 pages, 5 figures

Buzzard to Cardinal: Improved Mock Catalogs for Large Galaxy Surveys [CEA]

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http://arxiv.org/abs/2303.12104


We present the Cardinal mock galaxy catalogs, a new version of the Buzzard simulation that has been updated to support ongoing and future cosmological surveys, including DES, DESI, and LSST. These catalogs are based on a one-quarter sky simulation populated with galaxies out to a redshift of $z=2.35$ to a depth of $m_{\rm{r}}=27$. Compared to the Buzzard mocks, the Cardinal mocks include an updated subhalo abundance matching (SHAM) model that considers orphan galaxies and includes mass-dependent scatter between galaxy luminosity and halo properties. This model can simultaneously fit galaxy clustering and group–galaxy cross-correlations measured in three different luminosity threshold samples. The Cardinal mocks also feature a new color assignment model that can simultaneously fit color-dependent galaxy clustering in three different luminosity bins. We have developed an algorithm that uses photometric data to improve the color assignment model further and have also developed a novel method to improve small-scale lensing below the ray-tracing resolution. These improvements enable the Cardinal mocks to accurately reproduce the abundance of galaxy clusters and the properties of lens galaxies in the Dark Energy Survey data. As such, these simulations will be a valuable tool for future cosmological analyses based on large sky surveys. The cardinal mock will be released upon publication at https://chunhaoto.com/cardinalsim.

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C. To, J. DeRose, R. Wechsler, et. al.
Thu, 23 Mar 23
60/67

Comments: 37 pages; 20 figures. See figure 1 for summary and appendix K for a list of main differences between Cardinal and Buzzard. To be submitted to APJ; Comments welcome. Highlights can be found at this https URL

The first stars: formation, properties, and impact [CEA]

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http://arxiv.org/abs/2303.12500


The first generation of stars, often called Population III (or Pop III), form from metal-free primordial gas at redshifts 30 and below. They dominate the cosmic star formation history until redshifts 15 to 20, at which point the formation of metal-enriched Pop II stars takes over. We review current theoretical models for the formation, properties and impact of Pop III stars, and discuss existing and future observational constraints. Key takeaways from this review include the following: (1) Primordial gas is highly susceptible to fragmentation and Pop III stars form as members of small clusters with a logarithmically flat mass function. (2) Feedback from massive Pop III stars plays a central role in regulating subsequent star formation, but major uncertainties remain regarding its immediate impact. (3) In extreme conditions, supermassive Pop III stars can form, reaching masses of several 10^5 Msun. Their remnants may be the seeds of the supermassive black holes observed in high-redshift quasars. (4) Direct observations of Pop III stars in the early Universe remain extremely challenging. Indirect constraints from the global 21cm signal or gravitational waves are more promising. (5) Stellar archeological surveys allow us to constrain both the low-mass and the high-mass ends of the Pop III mass distribution. Observations suggest that most massive Pop III stars end their lives as core-collapse supernovae rather than as pair-instability supernovae.

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R. Klessen and S. Glover
Thu, 23 Mar 23
65/67

Comments: To appear in Annual Reviews of Astronomy and Astrophysics (75 pages, 14 figures, 500+ references)

Emulating radiation transport on cosmological scale using a denoising Unet [CEA]

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http://arxiv.org/abs/2303.12065


Semi-numerical simulations are the leading candidates for evolving reionization on cosmological scales. These semi-numerical models are efficient in generating large-scale maps of the 21cm signal, but they are too slow to enable inference at the field level. We present different strategies to train a U-Net to accelerate these simulations. We derive the ionization field directly from the initial density field without using the ionizing sources’ location, and hence emulating the radiative transfer process. We find that the U-Net achieves higher accuracy in reconstructing the ionization field if the input includes either white noise or a noisy version of the ionization map beside the density field during training. Our model reconstructs the power spectrum over all scales perfectly well. This work represents a step towards generating large-scale ionization maps with a minimal cost and hence enabling rapid parameter inference at the field level.

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M. Masipa, S. Hassan, M. Santos, et. al.
Wed, 22 Mar 23
6/68

Comments: 5 pages, 4 figures, Accepted at the ICLR 2023 Workshop on Physics for Machine Learning (Camera-ready version)

One-loop Corrections in Power Spectrum in Single Field Inflation [CEA]

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http://arxiv.org/abs/2303.12025


We revisit the one-loop correction in curvature perturbation power spectrum in models of single field inflation which undergo a phase of ultra slow-roll (USR) inflation. We include the contributions from both the cubic and quartic interaction Hamiltonians and calculate the one-loop corrections on the spectrum of the CMB scale modes from the small scale modes which leave the horizon during the USR phase. It is shown that the amplitude of one-loop corrections depends on the sharpness of the transition from the USR phase to the final slow-roll phase. For an arbitrarily sharp transition, the one-loop correction becomes arbitrarily large, invalidating the perturbative treatment of the analysis. We speculate that for a mild transition, the large one-loop corrections are washed out during the subsequent evolution after the USR phase. The implications for primordial black holes formation are briefly reviewed.

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H. Firouzjahi
Wed, 22 Mar 23
14/68

Comments: 26 pages, 1 Figure

Searching for Time-Dependent Axion Dark Matter Signals in Pulsars [CEA]

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http://arxiv.org/abs/2303.11792


Axion dark matter can be converted into photons in the magnetospheres of neutron stars leading to a spectral line centred on the Compton wavelength of the axion. Due to the rotation of the star and the plasma effects in the magnetosphere the signal is predicted to be periodic with significant time variation – a unique smoking gun for axion dark matter. As a proof of principle and to develop the methodology, we carry out the first time domain search of the signal using data from PSR J2144$-$3933 taken as part of the MeerTIME project on MeerKAT telescope. We search for specific signal templates using a matched filter technique and discuss when a time-domain analysis (as is typically the case in pulsar observations) gives greater sensitivity to the axion-coupling to photons in comparison to a simple time-averaged total flux study. We do not find any candidate signals and, hence, impose an upper limit on the axion-to-photon coupling of $g_{a\gamma\gamma}<4\times 10^{-11}\,{\rm GeV}^{-1}$ over the mass range $m_{\rm a}=3.9-4.7\,\mu{\rm eV}$ using this data. This limit relies on PSR J2144$-$3933 not being an extremely aligned rotator, as strongly supported by simple arguments based on the observed pulse profile width. We discuss the possibilities of improving this limit using future observations with MeerKAT and also SKA1-mid and the possibility of using other objects. Finally, to evade modelling uncertainties in axion radio signals, we also carry out a generic “any periodic-signal search” in the data, finding no evidence for an axion signal.

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R. Battye, M. Keith, J. McDonald, et. al.
Wed, 22 Mar 23
26/68

Comments: 21 pages, 14 figures Comments welcome

Barrow nearly-extensive Gibbs-like entropy favoured by the full dynamical and geometrical data set in cosmology [CEA]

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http://arxiv.org/abs/2303.11680


We apply the full set of most update dynamical and geometrical data in cosmology to the nonextensive Barrow entropic holographic dark energy. We show that the data point towards an extensive Gibbs-like entropic behaviour for the cosmological horizons, which is the extreme case of the Barrow entropy, with the entropy parameter being $\Delta > 0.86$, close to the maximum threshold of $\Delta =1$ where the fractal dimension of the area-horizon becomes almost or just the volume and the intensivity is recovered. Futhermore, we find that the standard Bekenstein area-entropy limit ($\Delta = 0$) is excluded by the set of our data. This contradicts the bounds obtained recently from early universe tests such as the baryon asymmetry, the big-bang nucleosynthesis, and the inflation limiting $\Delta< 0.008$ at the most extreme case.

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T. Denkiewicz, V. Salzano and M. Dabrowski
Wed, 22 Mar 23
37/68

Comments: 11 pages; 2 tables. Comments are welcome

Dark Matter Minihalos from Primordial Magnetic Fields [CEA]

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http://arxiv.org/abs/2303.11861


Primordial magnetic fields (PMF) can enhance baryon perturbations on scales below the photon mean free path. However, a magnetically driven baryon fluid becomes turbulent near recombination, thereby damping out baryon perturbations below the turbulence scale. In this letter, we show that the growth of baryon perturbations is imprinted in the dark matter perturbations, which are unaffected by turbulence and eventually collapse to form $10^{-11}-10^3\ M_{\odot}$ dark matter minihalos. In the process, we analytically derive the evolution of the PMF power spectrum in the viscous drag regime. If the magnetic fields purportedly detected in the blazar observations are PMFs generated after inflation and have a Batchelor spectrum, then such PMFs should also produce minihalos.

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P. Ralegankar
Wed, 22 Mar 23
53/68

Comments: 5 pages + 6 pages appendices

On the simulation of gravitational lensing [CEA]

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http://arxiv.org/abs/2303.11824


Gravitational lensing refers to the deflection of light by the gravity of celestial bodies, often predominantly composed of dark matter. Seen through a gravitational lens, the images of distant galaxies appear distorted. In this paper we discuss simulation of the image distortion by gravitational lensing. The objective is to enhance our understanding of how gravitational lensing works through a simple tool to visualise hypotheses. The simulator can also generate synthetic data for the purpose of machine learning, which will hopefully allow us to invert the distortion function, something which is not analytically possible at present.

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H. Schaatun, B. Normann, E. Austnes, et. al.
Wed, 22 Mar 23
61/68

Comments: 7 pages, 6 figures

Cosmological constraints with the linear point from the BOSS survey [CEA]

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http://arxiv.org/abs/2303.10661


The {\it Linear Point} (LP), defined as the midpoint between the BAO peak and the associated left dip of the two-point correlation function (2PCF), $\xi(s)$, is proposed as a new standard ruler which is insensitive to nonlinear effects. In this paper, we use a Bayesian sampler to measure the LP and estimate the corresponding statistical uncertainty, and then perform cosmological parameter constraints with LP measurements. Using the Patchy mock catalogues, we find that the measured LPs are consistent with theoretical predictions at 0.6 per cent level. We find constraints with midpoints identified from the rescaled 2PCF ($s^2 \xi$) more robust than those from the traditional LP based on $\xi$, as the BAO peak is not always prominent when scanning the cosmological parameter space, with the cost of 2–4 per cent increase of statistical uncertainty. This problem can also be solved by an additional dataset that provides strong parameter constraints. Measuring LP from the reconstructed data slightly increases the systematic error but significantly reduces the statistical error, resulting in more accurate measurements. The 1$\,\sigma$ confidence interval of distance scale constraints from LP measurements are 20–30 per cent larger than those of the corresponding BAO measurements. For the reconstructed SDSS DR12 data, the constraints on $H_0$ and $\Omega_{\rm m}$ in a flat-$\Lambda$CDM framework with the LP are generally consistent with those from BAO. When combined with Planck cosmic microwave background data, we obtain $H_0=68.02_{-0.37}^{+0.36}$ ${\rm km}\,{\rm s}^{-1}\,{\rm Mpc}^{-1}$ and $\Omega_{\rm m}=0.3055_{-0.0048}^{+0.0049}$ with the LP.

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M. He, C. Zhao and H. Shan
Tue, 21 Mar 23
18/68

Comments: 13 pages, 12 figures, submitted to MNRAS

Model selection results from different BAO datasets — DE models and $Ω_K$CDM [CEA]

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http://arxiv.org/abs/2303.11271


The use of the baryonic acoustic oscillations (BAO) datasets offers a unique opportunity to connect the early universe and the late one. In this proceeding, we discuss recent results that used a marginalised likelihood to remove the $H_0-r_d $ degeneracy and then tested it on different dark energy (DE) models. It was found that this approach which does not rely on calibration on $r_d$ or $H_0$, allows us to obtain results, comparable to the ones calculated with standard likelihoods. Here we emphasize on the major differences that we observed for the two different BAO datasets that we employed — a transversal one, containing only angular BAO measurements, and a mixed one, containing both angular and radial BAO measurements. We see that the two datasets have different statistical preferences for DE models and also different preference for the curvature of the universe.

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D. Staicova
Tue, 21 Mar 23
21/68

Comments: Prepared for the Proceedings of the “Corfu Summer Institute 2022 “School and Workshops on Elementary Particle Physics and Gravity””

Dark siren cosmology with binary black holes in the era of third-generation gravitational wave detectors [CEA]

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http://arxiv.org/abs/2303.10693


Third-generation (3G) gravitational wave detectors, in particular Einstein Telescope (ET) and Cosmic Explorer (CE), will explore unprecedented cosmic volumes in search for compact binary mergers, providing us with tens of thousands of detections per year. In this study, we simulate and employ binary black holes detected by 3G interferometers as dark sirens, to extract and infer cosmological parameters by cross-matching gravitational wave data with electromagnetic information retrieved from a simulated galaxy catalog. Considering a standard $\Lambda$CDM model, we apply a suitable Bayesian framework to obtain joint posterior distributions for the Hubble constant $H_0$ and the matter energy density parameter $\Omega_m$ in different scenarios. Assuming a galaxy catalog complete up to $z=1$ and dark sirens detected with a network signal-to-noise ratio greater than 300, we show that a network made of ET and two CEs can constrain $H_0$ ($\Omega_m$) to a promising $0.7\%$ ($9.0\%$) at $90\%$ confidence interval within one year of continuous observations. Additionally, we find that most of the information on $H_0$ is contained in local, single-host dark sirens, and that dark sirens at $z>1$ do not substantially improve these estimates. Our results imply that a sub-percent measure of $H_0$ can confidently be attained by a network of 3G detectors, highlighting the need for characterising all systematic effects to a higher accuracy.

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N. Muttoni, D. Laghi, N. Tamanini, et. al.
Tue, 21 Mar 23
30/68

Comments: 22 pages, 7 figures. Submitted to PRD

Physical evolution of dark matter halo around the depletion boundary [CEA]

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http://arxiv.org/abs/2303.10887


We investigate the build-up of the halo profile out to large scale in a cosmological simulation, focusing on the roles played by the recently proposed depletion radii. We explicitly show that halo growth is accompanied by the depletion of the environment, with the inner depletion radius demarcating the two. This evolution process is also observed via the formation of a trough in the bias profile, with the two depletion radii identifying key scales in the evolution. The ratio between the inner depletion radius and the virial radius is approximately a constant factor of 2 across redshifts and halo masses. The ratio between their enclosed densities is also close to a constant of 0.18. These simple scaling relations reflect the largely universal scaled mass profile on these scales, which only evolves weakly with redshift. The overall picture of the boundary evolution can be broadly divided into three stages according to the maturity of the depletion process, with cluster halos lagging behind low mass ones in the evolution. We also show that the traditional slow and fast accretion dichotomy of halo growth can be identified as accelerated and decelerated depletion phases respectively.

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H. Gao, J. Han, M. Fong, et. al.
Tue, 21 Mar 23
32/68

Comments: 13 pages, 10 figures

Statistical anisotropy in galaxy ellipticity correlations [CEA]

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http://arxiv.org/abs/2303.10890


As well as the galaxy number density and peculiar velocity, the galaxy intrinsic alignment can be used to test the cosmic isotropy. We study distinctive impacts of the isotropy breaking on the configuration-space two-point correlation functions (2PCFs) composed of the spin-2 galaxy ellipticity field. For this purpose, we build a methodology to efficiently compute general types of the isotropy-violating 2PCFs by generalizing the polypolar spherical harmonic decomposition approach to the spin-weighted version. As a demonstration, we analyze the 2PCFs when the matter power spectrum has a well-known $g_*$-type isotropy-breaking term (induced by, e.g., dark vector fields). We then confirm that some anisotropic distortions indeed appear in the 2PCFs and their shapes rely on a preferred direction causing the isotropy violation, $\hat{d}$. Such a feature can be a distinctive indicator for testing the cosmic isotropy. Comparing the isotropy-violating 2PCFs computed with and without the plane parallel (PP) approximation, we find that, depending on $\hat{d}$, the PP approximation is no longer valid when an opening angle between the directions towards target galaxies is ${\cal O}(1^\circ)$ for the density-ellipticity and velocity-ellipticity cross correlations and around $10^\circ$ for the ellipticity auto correlation. This suggests that an accurate test for the cosmic isotropy requires the formulation of the 2PCF without relying on the PP approximation.

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M. Shiraishi, T. Okumura and K. Akitsu
Tue, 21 Mar 23
37/68

Comments: 21+1 pages, 8 figures

A physical and concise halo model based on the depletion radius [CEA]

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http://arxiv.org/abs/2303.10886


We develop a self-consistent and accurate halo model by partitioning matter according to the depletion radii of haloes. Unlike conventional models that define haloes with the virial radius while relying on a separate exclusion radius or ad-hoc fixes to account for halo exclusion, our model distributes mass across all scales self-consistently. Using a cosmological simulation, we show that our halo definition leads to very simple and intuitive model components, with the one-halo term given by the Einasto profile with no truncation needed, and the halo-halo correlation function following a universal power-law form down to the halo boundary. The universal halo-halo correlation also allows us to easily model the distribution of unresolved haloes as well as diffuse matter. Convolving the halo profile with the halo-halo correlation function, we obtain a complete description of the halo-matter correlation across all scales, which self-consistently accounts for halo exclusion on the transition scale. Mass conservation is explicitly maintained in our model, and the scale dependence of the classical halo bias is easily reproduced. Our model can successfully reconstruct the halo-matter correlation function with percent level accuracy for halo virial masses in the range of $10^{11.5}h^{-1}{\rm M}{\odot}<M{\rm vir}<10^{15.35}h^{-1}{\rm M}_{\odot}$ at $z=0$, and covers the radial range of $0.01h^{-1}{\rm Mpc}<r<20h^{-1}{\rm Mpc}$. We also show that our model profile can accurately predict the characteristic depletion radius at the minimum bias and the splash-back radius at the steepest density slope locations.

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Y. Zhou and J. Han
Tue, 21 Mar 23
38/68

Comments: 19 pages, 19 figures

Non-Gaussian assembly bias from a semi-analytic galaxy formation model [CEA]

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http://arxiv.org/abs/2303.10337


We use $z=1$ mock galaxy catalogues produced with the semi-analytic code GALACTICUS to study the dependence of the non-Gaussian bias parameter $b_\phi$ on the mass assembly history of the host halos. We generate large sets of merger trees and measure the non-Gaussian assembly bias $\Delta b_\phi$ for galaxies selected by color magnitude and emission line luminosities. For galaxies selected by $g-r$ color, we find a large assembly bias consistent with the analysis of Barreira et al. (2020) based on hydro-dynamical simulations of galaxy formation. This effect arises from the fact that a larger value of the normalization amplitude $\sigma_8$ implies a faster mass assembly (at fixed halo mass) and, therefore, older and redder galaxies. On the contrary, for galaxies selected by their H$\alpha$ luminosity, we do not detect a significant assembly bias, at least at $z=1$ and in the halo mass range $3\times10^{10} < M < 10^{12}\ M_\odot$ considered here. This is presumably due to the fact that emission line strengths are mainly sensitive to the instantaneous star formation rate, which appears to depend weakly on $\sigma_8$ at $z=1$. This indicates that the non-Gaussian assembly bias should be less of a concern for future emission line galaxy surveys. We also investigate, for the first time, the sensitivity of the non-Gaussian assembly bias to a change in the parameters of the galaxy formation model that control the AGN and stellar feedback as well as the star formation rate. When these parameters change within a factor of two from their fiducial value, they induce variations up to order unity in the measured $\Delta b_\phi$, but the overall trends with color or luminosity remain the same. However, since these results may be sensitive to the choice of galaxy formation model, it will be prudent to extend this analysis to other semi-analytic models in addition to halo mass and redshift.

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M. Marinucci, V. Desjacques and A. Benson
Tue, 21 Mar 23
39/68

Comments: 11 pages. Comments are welcome

Planes of satellites, no longer in tension with LCDM [CEA]

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http://arxiv.org/abs/2303.10190


The arrangement of dwarf galaxies in a thin plane surrounding the Milky Way has been thought to contradict the prevailing cosmological model of cold dark matter in the Universe. New work suggests that this arrangement may just be a temporary alignment, bringing our galaxy back into agreement with theoretical expectations once the radial distribution of satellites is taken into account.

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L. Sales and J. Navarro
Tue, 21 Mar 23
60/68

Comments: Invited ‘News and Views’ contribution for Nature Astronomy on paper by Sawala et al. 2022 “The Milky Way’s plane of satellites is consistent with {\Lambda}CDM”

Primordial Gravitational Waves in non-Minimally Coupled Chromo-Natural Inflation [CEA]

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http://arxiv.org/abs/2303.10718


We consider inflation driven by an axion-like particle coupled to an SU(2) gauge sector via a Chern-Simons term. Known as chromo-natural inflation, this scenario is in tension with CMB observations. In order to remedy this fact and preserve both the symmetries and the intriguing gravitational wave phenomenology exhibited by the model, we explore the non-minimal coupling of the axion-inflaton to the Einstein tensor. We identify regions of parameter space corresponding to a viable cosmology at CMB scales. We also highlight the possibility of a large and chiral gravitational wave signal at small scales. This is of particular interest for gravitational wave interferometers.

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E. Dimastrogiovanni, M. Fasiello, M. Michelotti, et. al.
Tue, 21 Mar 23
64/68

Comments: 27 pages, 13 figures

Astrophysical and Cosmological Searches for Lorentz Invariance Violation [CEA]

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http://arxiv.org/abs/2303.10643


Lorentz invariance is one of the fundamental tenets of Special Relativity, and has been extensively tested with laboratory and astrophysical observations. However, many quantum gravity models and theories beyond the Standard Model of Particle Physics predict a violation of Lorentz invariance at energies close to Planck scale. This article reviews observational and experimental tests of Lorentz invariance violation (LIV) with photons, neutrinos and gravitational waves. Most astrophysical tests of LIV using photons are based on searching for a correlation of the spectral lag data with redshift and energy. These have been primarily carried out using compact objects such as pulsars, Active Galactic Nuclei (AGN), and Gamma-ray bursts (GRB). There have also been some claims for LIV from some of these spectral lag observations with GRBs, which however are in conflict with the most stringent limits obtained from other LIV searches. Searches have also been carried out using polarization measurements from GRBs and AGNs. For neutrinos, tests have been made using both astrophysical observations at MeV energies (from SN 1987A) as well as in the TeV-PeV energy range based on IceCube observations, atmospheric neutrinos, and long-baseline neutrino oscillation experiments. Cosmological tests of LIV entail looking for a constancy of the speed of light as a function of redshift using multiple observational probes, as well as looking for birefringence in Cosmic Microwave background observations. This article will review all of these aforementioned observational tests of LIV, including results which are in conflict with each other.

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S. Desai
Tue, 21 Mar 23
67/68

Comments: 31 pages. Comments welcome. Invited chapter for the edited book {\it Recent Progress on Gravity Tests: Challenges and Future Perspectives} (Eds. C. Bambi and A. C\’ardenas-Avenda\~no, Springer Singapore, expected in 2023)

Measuring galaxy cluster mass profiles into low acceleration regions with galaxy kinematics [CEA]

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http://arxiv.org/abs/2303.10175


We probe the outer dynamical mass profile of 16 galaxy clusters from the HIghest X-ray FLUx Galaxy Cluster Sample (HIFLUGCS) using galaxy kinematics. Numerically solving the spherical Jeans equation, we parameterize the dynamical mass profile and the galaxy velocity anisotropy profile using two general functions to ensure that our results are not biased towards any specific model. The mass-velocity anisotropy degeneracy is broken by using two “virial shape parameters” that depend on the fourth moment of velocity distribution. The resulting velocity anisotropy estimates consistently show a nearly isotropic distribution in the inner regions, with an increasing radial anisotropy towards large radii. We compare our derived dynamical masses with those calculated from X-ray gas data assuming hydrostatic equilibrium, finding that massive and rich relaxed clusters generally present consistent mass measurements, while unrelaxed or low-richness clusters have systematically larger total mass than hydrostatic mass by an average of 50\%. This might help alleviate current tensions in the measurement of $\sigma_8$, but it also leads to cluster baryon fractions below the cosmic value. Finally, our approach probes accelerations as low as $10^{-11}$ m s$^{-2}$, comparable to the outskirts of individual late-type galaxies. We confirm that galaxy clusters deviate from the radial acceleration relation defined by galaxies.

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P. Li, Y. Tian, M. Júlio, et. al.
Tue, 21 Mar 23
68/68

Comments: 13 pages, 8 figures, 1 table. Submitted to A&A

Aemulus $ν$: Precise Predictions for Matter and Biased Tracer Power Spectra in the Presence of Neutrinos [CEA]

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http://arxiv.org/abs/2303.09762


We present the Aemulus $\nu$ simulations: a suite of 150 $(1.05 h^{-1}\rm Gpc)^3$ $N$-body simulations with a mass resolution of $3.51\times 10^{10} \frac{\Omega_{cb}}{0.3} ~ h^{-1} M_{\odot}$ in a $w\nu$CDM cosmological parameter space. The simulations have been explicitly designed to span a broad range in $\sigma_8$ to facilitate investigations of tension between large scale structure and cosmic microwave background cosmological probes. Neutrinos are treated as a second particle species to ensure accuracy to $0.5\, \rm eV$, the maximum neutrino mass that we have simulated. By employing Zel’dovich control variates, we increase the effective volume of our simulations by factors of $10-10^5$ depending on the statistic in question. As a first application of these simulations, we build new hybrid effective field theory and matter power spectrum surrogate models, demonstrating that they achieve $\le 1\%$ accuracy for $k\le 1\, h\,\rm Mpc^{-1}$ and $0\le z \le 3$, and $\le 2\%$ accuracy for $k\le 4\, h\,\rm Mpc^{-1}$ for the matter power spectrum. We publicly release the trained surrogate models, and estimates of the surrogate model errors in the hope that they will be broadly applicable to a range of cosmological analyses for many years to come.

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J. DeRose, N. Kokron, A. Banerjee, et. al.
Mon, 20 Mar 23
3/51

Comments: 35 pages, 14 figures, to be submitted to JCAP

The Pantheon Sample analysis of cosmological constraints under new models [CEA]

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http://arxiv.org/abs/2303.10095


In this project, the cosmological parameters are determined by applying six cosmological models to fit the magnitude-redshift relation of the Pantheon Sample consisting of 1048 Type Ia supernovae (SNe Ia) in the range of $0.01 < z < 2.26$. Apart from the well-known flat $\Lambda$CDM model as well as other models that have been broadly studied, this project includes two new models, which are the $\textit{o}\textit{w}$CDM model and the $\textit{o}\textit{w}0\textit{w}_a$CDM model, to fully evaluate the correlations between the cosmological parameters by performing the MCMC algorithm and to explore the geometry and mass content of the Universe. Combining the measurements of the baryon acoustic oscillation (BAO) and the cosmic microwave background (CMB) with the SNe Ia constraints, the matter density parameter $\Omega_M = 0.328^{+0.018}{-0.026}$, the curvature of space parameter $\Omega_k = 0.0045^{+0.0666}{-0.0741}$, and the dark energy equation of state parameter $w = -1.120^{+0.143}{-0.185}$ are measured for the $\textit{o}\textit{w}$CDM model. When it comes to the $\textit{o}\textit{w}0\textit{w}_a$CDM model, if the parameter $\textit{w}$ is allowed to evolve with the redshift as $w = w_0 + w_a(1-a)$, the cosmological parameters are found to be $\Omega_M = 0.344^{+0.018}{-0.027}$, $\Omega_k = 0.0027^{+0.0665}{-0.0716}$, $w_0 = -0.739^{+0.336}{-0.378}$, and $w_a = -0.812^{+0.750}_{-0.678}$. The parameters of the $\textit{o}\textit{w}$CDM model and the $\textit{o}\textit{w}_0\textit{w}_a$CDM model are consistent with the literature results, although the parameter $\textit{w}$ is not well constrained in both models. The large uncertainties of the parameter $\textit{w}$ can be reduced by running more steps for the MCMC algorithm to better constrain the parameters and estimate their uncertainties.

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P. Peng
Mon, 20 Mar 23
4/51

Comments: 9 pages, 9 figures, 2 tables

An accurate fluid approximation for massive neutrinos in cosmology [CEA]

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http://arxiv.org/abs/2303.09580


A measurement of the neutrino mass scale will be achieved with cosmological probes in the upcoming decade. On one hand, the inclusion of massive neutrinos in the linear perturbation theory of cosmological structure formation is well understood and can be done accurately with state of the art Boltzmann solvers. On the other hand, the numerical implementation of the Boltzmann equation is computationally expensive and is a bottleneck in those codes. This has motivated the development of more efficient fluid approximations, despite their limited accuracy over all scales of interest, $k \sim (10^{-3}-10)$Mpc$^{-1}$. In this work we account for the dispersive nature of the neutrino fluid, i.e., the scale dependence in the sound speed, leading to an improved fluid approximation. We show that overall $\lesssim 5\%$ errors can be achieved for the neutrino density and velocity transfer functions at redshift $z \lesssim 5$, which corresponds to an order of magnitude improvement over previous approximation schemes that can be discrepant by as much as a factor of two.

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C. Nascimento
Mon, 20 Mar 23
9/51

Comments: 10+8 pages, 7 figures. Comments are welcome!

Model-independent bubble wall velocities in local thermal equilibrium [CEA]

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http://arxiv.org/abs/2303.10171


Accurately determining bubble wall velocities in first-order phase transitions is of great importance for the prediction of gravitational wave signals and the matter-antimatter asymmetry. However, it is a challenging task which typically depends on the underlying particle physics model. Recently, it has been shown that assuming local thermal equilibrium can provide a good approximation when calculating the bubble wall velocity. In this paper, we provide a model-independent determination of bubble wall velocities in local thermal equilibrium. Our results show that, under the reasonable assumption that the sound speeds in the plasma are approximately uniform, the hydrodynamics can be fully characterized by four quantities: the phase strength $\alpha_n$, the ratio of the enthalpies in the broken and symmetric phases, $\Psi_n$, and the sound speeds in both phases, $c_s$ and $c_b$. We provide a code snippet that allows for a determination of the wall velocity and energy fraction in local thermal equilibrium in any model. In addition, we present a fit function for the wall velocity in the case $c_s = c_b = 1/\sqrt 3$.

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W. Ai, B. Laurent and J. Vis
Mon, 20 Mar 23
12/51

Comments: 32 pages, 5 figures

Cosmology inference at the field level from biased tracers in redshift-space [CEA]

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http://arxiv.org/abs/2303.09876


Cosmology inference of galaxy clustering at the field level with the EFT likelihood in principle allows for extracting all non-Gaussian information from quasi-linear scales, while robustly marginalizing over any astrophysical uncertainties. A pipeline in this spirit is implemented in the \texttt{LEFTfield} code, which we extend in this work to describe the clustering of galaxies in redshift space. Our main additions are: the computation of the velocity field in the LPT gravity model, the fully nonlinear displacement of the evolved, biased density field to redshift space, and a systematic expansion of velocity bias. We test the resulting analysis pipeline by applying it to synthetic data sets with a known ground truth at increasing complexity: mock data generated from the perturbative forward model itself, sub-sampled matter particles, and dark matter halos in N-body simulations. By fixing the initial-time density contrast to the ground truth, while varying the growth rate $f$, bias coefficients and noise amplitudes, we perform a stringent set of checks. These show that indeed a systematic higher-order expansion of the velocity bias is required to infer a growth rate consistent with the ground truth within errors. Applied to dark matter halos, our analysis yields unbiased constraints on $f$ at the level of a few percent for a variety of halo masses at redshifts $z=0,\,0.5,\,1$ and for a broad range of cutoff scales $0.08\,h/\mathrm{Mpc} \leq \Lambda \leq 0.20\,h/\mathrm{Mpc}$. Importantly, deviations between true and inferred growth rate exhibit the scaling with halo mass, redshift and cutoff that one expects based on the EFT of Large Scale Structure. Further, we obtain a robust detection of velocity bias through its effect on the redshift-space density field and are able to disentangle it from higher-derivative bias contributions.

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J. Stadler, F. Schmidt and M. Reinecke
Mon, 20 Mar 23
15/51

Comments: N/A

RXJ0437+00: Constraining Dark Matter with Exotic Gravitational Lenses [CEA]

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http://arxiv.org/abs/2303.09568


We present the first strong-gravitational-lensing analysis of the galaxy cluster RXJ0437.1+0043 (RXJ0437; z = 0.285). Newly obtained, deep MUSE observations, Keck/MOSFIRE near-infrared spectroscopy, and Hubble Space Telescope SNAPshot imaging reveal 13 multiply imaged background galaxies, three of them (at z=1.98, 2.97, and 6.02, respectively) in hyperbolic umbilic (H-U) lensing configurations. The H-U images are located only 20 — 50 kpc from the cluster centre, i.e., at distances well inside the Einstein radius where images from other lens configurations are demagnified and often unobservable. Extremely rare (only one H-U lens was known previously) these systems are able to constrain the inner slope of the mass distribution — and unlike radial arcs, the presence of H-U configurations is not biased towards shallow cores. The galaxies lensed by RXJ0437 are magnified by factors ranging from 30 to 300 and (in the case of H-U systems) stretched nearly isotropically. Taking advantage of this extreme magnification, we demonstrate how the source galaxies in H-U systems can be used to probe for small-scale ($\sim 10^{9} M_{\odot}$) substructures, providing additional insight into the nature of dark matter.

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D. Lagattuta, J. Richard, H. Ebeling, et. al.
Mon, 20 Mar 23
22/51

Comments: 17 pages, 13 figures, 3 tables (including 1 in an appendix). Accepted in MNRAS

DEMNUni: The imprint of massive neutrinos on the cross-correlation between cosmic voids and CMB lensing [CEA]

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http://arxiv.org/abs/2303.10048


Cosmic voids are a powerful probe of cosmology and are one of the core observables of upcoming galaxy surveys. The cross-correlations between voids and other large-scale structure tracers such as galaxy clustering and galaxy lensing have been shown to be very sensitive probes of cosmology and among the most promising to probe the nature of gravity and the neutrino mass. However, recent measurements of the void imprint on the lensed Cosmic Microwave Background (CMB) have been shown to be in tension with expectations based on LCDM simulations, hinting to a possibility of non-standard cosmological signatures due to massive neutrinos. In this work we use the DEMNUni cosmological simulations with massive neutrino cosmologies to study the neutrino impact on voids selected in photometric surveys, e.g. via Luminous Red Galaxies, as well as on the void- CMB lensing cross-correlation. We show how the void properties observed in this way (size function, profiles) are affected by the presence of massive neutrinos compared to the neutrino massless case, and show how these can vary as a function of the selection method of the void sample. We comment on the possibility for massive neutrinos to be the source of the aforementioned tension. Finally, we identify the most promising setup to detect signatures of massive neutrinos in the voids-CMB lensing cross-correlation and define a new quantity useful to distinguish among different neutrino masses by comparing future observations against predictions from simulations including massive neutrinos.

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P. Vielzeuf, M. Calabrese, C. Carbone, et. al.
Mon, 20 Mar 23
37/51

Comments: 34 pages, 15 figures

Euclid: Validation of the MontePython forecasting tools [CEA]

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http://arxiv.org/abs/2303.09451


The Euclid mission of the European Space Agency will perform a survey of weak lensing cosmic shear and galaxy clustering in order to constrain cosmological models and fundamental physics. We expand and adjust the mock Euclid likelihoods of the MontePython software in order to match the exact recipes used in previous Euclid Fisher matrix forecasts for several probes: weak lensing cosmic shear, photometric galaxy clustering, the cross-correlation between the latter observables, and spectroscopic galaxy clustering. We also establish which precision settings are required when running the Einstein-Boltzmann solvers CLASS and CAMB in the context of Euclid. For the minimal cosmological model, extended to include dynamical dark energy, we perform Fisher matrix forecasts based directly on a numerical evaluation of second derivatives of the likelihood with respect to model parameters. We compare our results with those of other forecasting methods and tools. We show that such MontePython forecasts agree very well with previous Fisher forecasts published by the Euclid Collaboration, and also, with new forecasts produced by the CosmicFish code, now interfaced directly with the two Einstein-Boltzmann solvers CAMB and CLASS. Moreover, to establish the validity of the Gaussian approximation, we show that the Fisher matrix marginal error contours coincide with the credible regions obtained when running Monte Carlo Markov Chains with MontePython while using the exact same mock likelihoods. The new Euclid forecast pipelines presented here are ready for use with additional cosmological parameters, in order to explore extended cosmological models.

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S. Casas, J. Lesgourgues, N. Schöneberg, et. al.
Fri, 17 Mar 23
6/67

Comments: 45 pages, 24 figures

Analysis of Dark Matter Halo Structure Formation in $N$-body Simulations with Machine Learning [CEA]

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http://arxiv.org/abs/2303.09098


The properties of the matter density field in the initial conditions have a decisive impact on the features of the large-scale structure of the Universe as observed today. These need to be studied via $N$-body simulations, which are imperative to analyze high density collapsed regions into dark matter halos. In this paper, we train Machine Learning algorithms with information from N -body simulations to infer two properties: dark matter particle halo classification that leads to halo formation prediction with the characteristics of the matter density field traced back to the initial conditions, and dark matter halo formation by calculating the Halo Mass Function (HMF), which offers the number density of dark matter halos with a given threshold. We map the initial conditions of the matter density field into classification labels of dark matter halo structures. The Halo Mass Function of the simulations is calculated and reconstructed with theoretical methods as well as our trained algorithms. We test several Machine Learning techniques where we could find that the Random Forest and Neural Networks proved to be the better performing tools to classify dark matter particles in cosmological simulations. We also show that that it is not compulsory to use a high amount of data to train the algorithms in order to reconstruct the HMF, giving us a very good fitting function for both simulation and theoretical results.

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J. Chacón, I. Gómez-Vargas, R. Méndez, et. al.
Fri, 17 Mar 23
9/67

Comments: 10 pages, 6 figures

Optimal Estimation of the Binned Mask-Free Power Spectrum, Bispectrum, and Trispectrum on the Full Sky [CEA]

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http://arxiv.org/abs/2303.08828


We derive optimal estimators for the two-, three-, and four-point correlators of statistically isotropic scalar fields defined on the sphere, such as the Cosmic Microwave Background temperature fluctuations, allowing for arbitrary (linear) masking and inpainting schemes. In each case, we give the optimal unwindowed estimator (obtained via a maximum-likelihood prescription, with an associated Fisher deconvolution matrix), and an idealized form, and pay close attention to their efficient computation. For the trispectrum, we include both parity-even and parity-odd contributions, as allowed by symmetry. The estimators can include arbitrary weighting of the data (and remain unbiased), but are shown to be optimal in the limit of inverse-covariance weighting and Gaussian statistics. The normalization of the estimators is computed via Monte Carlo methods, with the rate-limiting steps (involving spherical harmonic transforms) scaling linearly with the number of bins. An accompanying code package, PolyBin, implements these estimators in Python, and we demonstrate the estimators’ efficacy via a suite of validation tests.

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O. Philcox
Fri, 17 Mar 23
10/67

Comments: 33 pages, 10 figures, code available at this https URL

The e-MANTIS emulator: fast predictions of the non-linear matter power spectrum in $f(R)$CDM cosmology [CEA]

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http://arxiv.org/abs/2303.08899


In order to probe modifications of gravity at cosmological scales, one needs accurate theoretical predictions. N-body simulations are required to explore the non-linear regime of structure formation but are very time consuming. In this work, we build an emulator, dubbed e-MANTIS, that performs an accurate and fast interpolation between the predictions of a given set of cosmological simulations, in $f(R)$ modified gravity, run with ECOSMOG. We sample a wide 3D parameter space given by the current background scalar field value $10^{-7} < \left|f_{R_0} \right| < 10^{-4}$, matter density $0.24<\Omega_\mathrm{m}<0.39$, and primordial power spectrum normalisation $0.6<\sigma_8<1.0$, with 110 points sampled from a Latin Hypercube. For each model we perform pairs of $f(R)$CDM and $\Lambda$CDM simulations covering an effective volume of $\left(560 \, h^{-1}\mathrm{Mpc}\right)^3$ with a mass resolution of $\sim 2 \times 10^{10} h^{-1} M_\odot$. We compute the matter power spectrum boost due to $f(R)$ gravity $B(k)=P_{f(R)}(k)/P_{\Lambda\mathrm{CDM}}(k)$ and build an emulator using a Gaussian Process Regression method. The boost is mostly independent of $h$, $n_{s}$, and $\Omega_{b}$, which reduces the dimensionality of the relevant cosmological parameter space. Additionally, it is much more robust against statistical and systematic errors than the raw power spectrum, thus strongly reducing our computational needs. The resulting emulator has a maximum error of $3\%$ across the whole cosmological parameter space, for scales $0.03 \ h\mathrm{Mpc}^{-1} < k < 7 \ h\mathrm{Mpc}^{-1}$, and redshifts $0 < z < 2$, while in most cases the accuracy is better than $1\%$. Such an emulator could be used to constrain $f(R)$ gravity with weak lensing analyses.

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I. Sáez-Casares, Y. Rasera and B. Li
Fri, 17 Mar 23
11/67

Comments: N/A

Revisiting Vainshtein Screening for fast N-body simulations [CEA]

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http://arxiv.org/abs/2303.09549


We revisit a method to incorporate the Vainshtein screening mechanism in N-body simulations proposed by R. Scoccimarro in~\cite{Scoccimarro:2009eu}. We further extend this method to cover a subset of Horndeski theories that evade the bound on the speed of gravitational waves set by the binary neutron star merger GW170817. The procedure consists of the computation of an effective gravitational coupling that is time and scale dependent, $G_{\rm eff}\left(k,z\right)$, where the scale dependence will incorporate the screening of the fifth-force. This is a fast procedure that when contrasted to the alternative of solving the full equation of motion for the scalar field inside N-body codes, reduces considerably the computational time and complexity required to run simulations. To test the validity of this approach in the non-linear regime, we have implemented it in a COmoving Lagrangian Approximation (COLA) N-body code, and ran simulations for two gravity models that have full N-body simulation outputs available in the literature, nDGP and Cubic Galileon. We validate the combination of the COLA method with this implementation of the Vainshtein mechanism with full N-body simulations for predicting the boost function: the ratio between the modified gravity non-linear matter power spectrum and its General Relativity counterpart. This quantity is of great importance for building emulators in beyond-$\Lambda$CDM models, and we find that the method described in this work has an agreement of below $2\%$ for scales down to $k \approx 3h/$Mpc with respect to full N-body simulations.

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G. Brando, K. Koyama and H. Winther
Fri, 17 Mar 23
14/67

Comments: 33 pages, 13 figures and 9 tables

Learning to Concentrate: Multi-tracer Forecasts on Local Primordial Non-Gaussianity with Machine-Learned Bias [CEA]

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http://arxiv.org/abs/2303.08901


Local primordial non-Gaussianity (LPNG) is predicted by many non-minimal models of inflation, and creates a scale-dependent contribution to the power spectrum of large-scale structure (LSS) tracers, whose amplitude is characterized by $b_{\phi}$. Knowledge of $b_{\phi}$ for the observed tracer population is therefore crucial for learning about inflation from LSS. Recently, it has been shown that the relationship between linear bias $b_1$ and $b_{\phi}$ for simulated halos exhibits significant secondary dependence on halo concentration. We leverage this fact to forecast multi-tracer constraints on $f_{NL}^{\mathrm{loc}}$. We train a machine learning model on observable properties of simulated Illustris-TNG galaxies to predict $b_{\phi}$ for samples constructed to approximate DESI emission line galaxies (ELGs) and luminous red galaxies (LRGs). We find $\sigma(f_{NL}^{\mathrm{loc}}) = 2.3$, and $\sigma(f_{NL}^{\mathrm{loc}}) = 3.7$, respectively. These forecasted errors are roughly factors of 3, and 35\% improvements over the single-tracer case for each sample, respectively. When considering both ELGs and LRGs in their overlap region, we forecast $\sigma(f_{NL}^{\mathrm{loc}}) = 1.5$ is attainable with our learned model, more than a factor of 3 improvement over the single-tracer case, while the ideal split by $b_{\phi}$ could reach $\sigma(f_{NL}^{\mathrm{loc}}) <1$. We also perform multi-tracer forecasts for upcoming spectroscopic surveys targeting LPNG (MegaMapper, SPHEREx) and show that splitting tracer samples by $b_{\phi}$ can lead to an order-of-magnitude reduction in projected $\sigma(f_{NL}^{\mathrm{loc}})$ for these surveys.

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J. Sullivan, T. Prijon and U. Seljak
Fri, 17 Mar 23
35/67

Comments: 32 pages, 9 figures, 4 tables, to be submitted to JCAP

Rapidly growing primordial black holes as seeds of the massive high-redshift JWST Galaxies [CEA]

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http://arxiv.org/abs/2303.09391


A group of massive galaxies at redshifts of $z\geq 6.5$ have been recently detected by James Webb Space Telescope (JWST), which were unexpected to form at such early times within the standard Big Bang cosmology. In this work we propose that the formation of some $\sim 50~M_\odot$ primordial black holes (PBHs) formed in the early Universe via super-Eddington accretion within the dark matter halo can explain these observations. These PBHs may act as seeds for early galaxies formation with masses of $\sim 10^{9}-10^{10}~M_\odot$ at $z\sim 8$, hence accounting for the JWST observations. We use a hierarchical Bayesian inference framework to constrain the PBH mass distribution models, and find that the Lognormal model with the $M_{\rm c}\sim 35M_\odot$ is strongly preferred over other hypotheses. These rapidly growing BHs are expected to have strong radiation and may appear as the high-redshift compact objects, similar to those recently discovered by JWST.

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G. Yuan, L. Lei, Y. Wang, et. al.
Fri, 17 Mar 23
54/67

Comments: 7 pages, 4 figures, 2 tables, comments are welcome

The magnificent ACT of flavor-specific neutrino self-interaction [CEA]

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http://arxiv.org/abs/2303.08843


We revisit the cosmology of neutrino self-interaction and use the latest cosmic microwave background data from the Atacama Cosmology Telescope (ACT) and the Planck experiment to constrain the interaction strength. In both flavor-universal and nonuniversal coupling scenarios, we find that the ACT data prefers strong neutrino self-interaction that delays neutrino free streaming until just before the matter-radiation equality. When combined with the Planck 2018 data, the preference for strong interaction decreases due to the Planck polarization data. For the combined dataset, the flavor-specific interaction still provides a better fit to the CMB data than $\Lambda$CDM. This trend persists even when neutrino mass is taken into account and extra radiation is added. We also study the prospect of constraining such strong interaction by future terrestrial and space telescopes, and find that the upcoming CMB-S4 experiment will improve the upper limit on neutrino self-interaction by about a factor of three.

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A. Das and S. Ghosh
Fri, 17 Mar 23
63/67

Comments: 34 pages, 17 figures, 9 tables, carbon footprint estimation included

The Planck clusters in the LOFAR sky: IV: LoTSS-DR2: statistics of radio halos and re-acceleration models [CEA]

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http://arxiv.org/abs/2301.08052


Diffuse cluster-scale synchrotron radio emission is discovered in an increasing number of galaxy clusters in the form of radio halos (RHs), probing the presence of relativistic electrons and magnetic fields in the intra-cluster medium. The favoured scenario to explain their origin is that they trace turbulent regions generated during cluster mergers where particles are re-accelerated. In this framework, RHs are expected to probe cluster dynamics and are predicted to be more frequent in massive systems. Statistical studies are important to study the connection of RHs with cluster dynamics and to constrain theoretical models. Furthermore, low-frequency surveys can shed light on the existence of RHs with very steep radio-spectra, a key prediction of turbulent models. We study the properties of RHs from clusters of the second catalog of Planck Sunyaev Zel’dovich detected sources that lie within the 5634 deg^2 covered by the second Data Release (DR2) of the LOFAR Two-meter Sky Survey. We find that the number of observed RHs, their radio flux density and redshift distributions are in line with what is expected in the framework of the re-acceleration scenario. In addition, the fraction of clusters with RHs increases with the cluster mass, confirming the leading role of the gravitational process of cluster formation in the generation of RHs. These models predict a large fraction of RHs with very steep spectrum in the DR2 Planck sample, this will be tested in future studies, yet a comparison of the occurrence of halos in GMRT and LOFAR samples indeed shows a larger occurrence of RHs at lower frequencies suggesting the presence of a number of very steep spectrum RH that is preferentially detected by LOFAR. Using morphological information we confirm that RHs are preferentially located in merging systems and that the fraction of newly LOFAR discovered RHs is larger in less disturbed systems.

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R. Cassano, V. Cuciti, G. Brunetti, et. al.
Fri, 20 Jan 23
20/72

Comments: 12 pages, 10 figures, accepted for publication in A&A

The Planck clusters in the LOFAR sky VI. LoTSS-DR2: Properties of radio relics [CEA]

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http://arxiv.org/abs/2301.07814


Context. It is well-established that shock waves in the intracluster medium launched by galaxy cluster mergers can produce synchrotron emission, which is visible to us at radio frequencies as radio relics. However, the particle acceleration mechanism producing these relics is still not fully understood. It is also unclear how relics relate to radio halos, which trace merger-induced turbulence in the intracluster medium. Aims. We aim to perform the first statistical analysis of radio relics in a mass-selected sample of galaxy clusters, using homogeneous observations. Methods. We analysed all relics observed by the Low Frequency Array Two Metre Sky Survey Data Release 2 (LoTSS DR2) at 144 MHz, hosted by galaxy clusters in the second Planck catalogue of SZ sources (PSZ2). We measured and compared the relic properties in a uniform, unbiased way. In particular, we developed a method to describe the characteristic downstream width in a statistical manner. Additionally, we searched for differences between radio relic-hosting clusters with and without radio halos. Results. We find that, in our sample, $\sim$ 10% of galaxy clusters host at least one radio relic. We confirm previous findings, at higher frequencies, of a correlation between the relic-cluster centre distance and the longest linear size, as well as the radio relic power and cluster mass. However, our findings suggest that we are still missing a population of low-power relics. We also find that relics are wider than theoretically expected, even with optimistic downstream conditions. Finally, we do not find evidence of a single property that separates relic-hosting clusters with and without radio halos.

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A. Jones, F. Gasperin, V. Cuciti, et. al.
Fri, 20 Jan 23
46/72

Comments: 28 pages, 17 figures. Accepted for publication in A&A

New late-time constraints on $f(R)$ gravity [CEA]

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http://arxiv.org/abs/2301.07897


Modification of general relativity (GR) inspired by theories like $f(R)$ gravity is among the most popular ones to explain the late-time acceleration of the Universe as an alternative to the $\Lambda$CDM model. In this work, we use the state-of-the-art BAO+BBN data and the most recent Type Ia supernovae (SNe Ia) sample namely PantheonPlus, including the Cepheid host distances and covariance from SH0ES samples, to robustly constrain the $f(R)$ gravity framework via two of the most popular $f(R)$ models in literature, namely, the Hu-Sawicki and Starobinsky models. Additionally, we consider how the time variation of the Newton’s gravitational constant affects the supernovae distance modulus relation. We find a minor evidence for $f(R)$ gravity under the Hu-Sawicki dynamics from BAO+BBN and BAO+BBN+uncalibrated supernovae joint analysis, but the inclusion of Cepheid host distances, makes the model compatible with GR. Further, we notice tendency of this model to relax the $H_0$ tension. In general, in all the analyses carried out in this study with the late time probes, we find both the $f(R)$ models to be consistent with GR at 95\% CL.

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S. Kumar, R. Nunes, S. Pan, et. al.
Fri, 20 Jan 23
50/72

Comments: 9 pages, 3 figures, 1 table

Redshift evolution of cosmic birefringence in CMB anisotropies [CEA]

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http://arxiv.org/abs/2301.07971


We study the imprints of a cosmological redshift-dependent pseudoscalar field $\phi$ on the rotation of cosmic microwave background (CMB) linear polarization generated by a coupling $ \phi F^{\mu\nu} \tilde F_{\mu \nu}$. We show how either phenomenological or theoretically motivated redshift dependence of the pseudoscalar field, such as those in models of Early Dark Energy, Quintessence or axion-like dark matter, lead to CMB polarization and temperature-polarization power spectra which exhibit a multipole dependence which goes beyond the widely adopted approximation in which the redshift dependence of the linear polarization angle is neglected. Because of this multipole dependence, the isotropic birefringence effect due to a general coupling $\phi F^{\mu\nu} \tilde F_{\mu \nu}$ is not degenerate with a systematic calibration angle uncertainty. By taking this multipole dependence into account, we calculate the parameters of these phenomenological and theoretical redshift dependence of the pseudoscalar field which can be detected by future CMB polarization experiments on the basis of a $\chi^2$ analysis for a Wishart likelihood. As a final example of our approach, we compute by Markov Chain MonteCarlo (MCMC) the minimal coupling $g_\phi$ in Early Dark Energy which could be detected by future experiments, with or without marginalizing on a systematic rotation angle uncertainty.

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M. Galaverni, F. Finelli and D. Paoletti
Fri, 20 Jan 23
53/72

Comments: 18 pages, 16 figures

Morphological Analysis of the Polarized Synchrotron Emission with WMAP and Planck [CEA]

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http://arxiv.org/abs/2301.08041


The bright polarized synchrotron emission, away from the Galactic plane, originates mostly from filamentary structures. We implement a filament finder algorithm which allows the detection of bright elongated structures in polarized intensity maps. We analyse the sky at 23 and 30~GHz as observed respectively by \textit{WMAP} and \textit{Planck}. We identify 19 filaments, 13 of which have been previously observed. For each filament, we study the polarization fraction, finding values typically larger than for the areas outside the filaments, excluding the Galactic plane, and a fraction of about 30\% is reached in two filaments. We study the polarization spectral indices of the filaments, and find a spectral index consistent with the values found in previous analysis (about -3.1) for more diffuse regions. Decomposing the polarization signals into the $E$ and $B$ families, we find that most of the filaments are detected in $P_E$, but not in $P_B$. We then focus on understanding the statistical properties of the diffuse regions of the synchrotron emission at 23~GHz. Using Minkowski functionals and tensors, we analyse the non-Gaussianity and statistical isotropy of the polarized intensity maps. For a sky coverage corresponding to 80\% of the fainter emission, and on scales smaller than 6 degrees ($\ell > 30$), the deviations from Gaussianity and isotropy are significantly higher than 3$\sigma$. The level of deviation decreases for smaller scales, however, it remains significantly high for the lowest analised scale ($\sim 1.5^\circ$). When 60\% sky coverage is analysed, we find that the deviations never exceed 3$\sigma$. Finally, we present a simple data-driven model to generate non-Gaussian and anisotropic simulations of the synchrotron polarized emission. The simulations are fitted in order to match the spectral and statistical properties of the faintest 80\% sky coverage of the data maps.

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F. Martire, A. Banday, E. Martínez-González, et. al.
Fri, 20 Jan 23
55/72

Comments: 33 pages, 17 figures

Circular Polarization of the Astrophysical Gravitational Wave Background [CEA]

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http://arxiv.org/abs/2301.08205


The circular polarization of gravitational waves is a powerful observable to test parity violation in gravity and to distinguish between the primordial or the astrophysical origin of the stochastic background. This property comes from the expected unpolarized nature of the homogeneous and isotropic astrophysical background, contrary to some specific cosmological sources that can produce a polarized background. However, in this work we show that there is a non-negligible amount of circular polarization also in the astrophysical background, generated by Poisson fluctuations in the number of unresolved sources, which can be detected by the third-generation interferometers with signal-to-noise ratio larger than one. We also explain in which cases the gravitational wave maps can be cleaned from this extra source of noise, exploiting the frequency and the angular dependence, in order to search for signals from the early Universe. Future studies about the detection of polarized cosmological backgrounds with ground- and space-based interferometers should account for the presence of such a foreground contribution.

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L. Dall’Armi, A. Nishizawa, A. Ricciardone, et. al.
Fri, 20 Jan 23
64/72

Comments: 10 pages, 1 figure

The Planck clusters in the LOFAR sky. II. LoTSS-DR2: Recovering diffuse extended emission with LOFAR [CEA]

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http://arxiv.org/abs/2301.08121


Extended radio sources in the sky require a dense sampling of short baselines to be properly imaged by interferometers. This problem arises in many areas of radio astronomy, such as in the study of galaxy clusters, which may host Mpc-scale diffuse synchrotron sources in the form of radio halos. In clusters where no radio halos are detected, owing to intrinsic absence of emission or extrinsic (instrumental and/or observational) effects, it is possible to determine upper limits. We consider a sample of Planck galaxy clusters from the Second Data Release of the LOFAR Two Meter Sky Survey (LoTSS-DR2) where no radio halos are detected. We use this sample to test the capabilities of LOFAR to recover diffuse extended emission and derive upper limits. Through the injection technique, we simulate radio halos with various surface brightness profiles. We then predict the corresponding visibilities and image them along with the real visibilities. This method allows us to test the fraction of flux density losses owing to inadequate uv-coverage and obtain thresholds at which the mock emission becomes undetectable by visual inspection. The dense uv-coverage of LOFAR at short spacings allows to recover $\gtrsim90\%$ of the flux density of targets with sizes up to $\sim 15’$. We find a relation that provides upper limits based on the image noise and extent (in terms of number of beams) of the mock halo. This relation can be safely adopted to obtain upper limits without injecting when artifacts introduced by the subtraction of the discrete sources are negligible in the central region of the cluster. Otherwise, the injection process and visual inspection of the images are necessary to determine more reliable limits. Through these methods, we obtain upper limits for 75 clusters to be exploited in ongoing statistical studies.

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L. Bruno, G. Brunetti, A. Botteon, et. al.
Fri, 20 Jan 23
67/72

Comments: 20 pages (including Appendices). 21 Figures. 4 Tables. First submitted to A&A on 20/07/2022. Re-submission on 20/11/2022 after positive report of 26/09/2022. For the project Webpage see this https URL

Cosmic metal invaders: Intergalactic OVII as a tracer of the warm-hot intergalactic medium within cosmic filaments in the EAGLE simulation [CEA]

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http://arxiv.org/abs/2301.07771


The current observational status of the hot (log T(K) > 5.5) warm-hot intergalactic medium (WHIM) remains incomplete. While recent observations from stacking large numbers of Cosmic Web filaments have yielded statistically significant detections, direct measurements of single objects remain scarce. The lack of such a sample currently prevents a robust analysis of the cosmic baryon content composed of the hot WHIM, which could help solve the cosmological missing baryons problem. To improve the search for the missing baryons, we used the EAGLE simulation. Our aim is to understand the metal enrichment and distribution of highly ionised metals in the Cosmic Web. We detected the filaments by applying the Bisous formalism to the simulated galaxies, and characterised the spatial distributions as well as mass and volume fractions of the filamentary oxygen and OVII. We then constructed OVII column density maps and determined their detectability with Athena X-IFU. However, the oxygen and OVII number densities drop fast beyond the virial radii of haloes, falling below detectable levels at 700 kpc. Thus, only ~1% of the filament volumes are filled with OVII at detectable densities. This non-homogeneous distribution of the OVII complicates its usage for tracing the missing baryons. Instead, OVII forms narrow envelopes around haloes. This localised nature results in a low chance (10-20% per sight line) of detecting intergalactic OVII with Athena X-IFU within the SDSS catalogue of filaments. With future filament samples from the 4MOST survey, the chances increase up to a level of ~50%. Nonetheless, based on EAGLE results, this would not be enough to conclusively solve the missing baryon problem, as it would be limited to a few times the virial radii of haloes. Fortunately, the volumes around haloes are dense in hot WHIM, and tracing it could reduce the content of baryons still missing by ~25%.

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T. Tuominen, J. Nevalainen, P. Heinämäki, et. al.
Fri, 20 Jan 23
68/72

Comments: 17 pages, 13 figures, accepted for publication in Astronomy and Astrophysics. For associated video, see this https URL

Strong gravitational lensing and microlensing of supernovae [CEA]

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http://arxiv.org/abs/2301.07729


Strong gravitational lensing and microlensing of supernovae (SNe) are emerging as a new probe of cosmology and astrophysics in recent years. We provide an overview of this nascent research field, starting with a summary of the first discoveries of strongly lensed SNe. We describe the use of the time delays between multiple SN images as a way to measure cosmological distances and thus constrain cosmological parameters, particularly the Hubble constant, whose value is currently under heated debates. New methods for measuring the time delays in lensed SNe have been developed, and the sample of lensed SNe from the upcoming Rubin Observatory Legacy Survey of Space and Time (LSST) is expected to provide competitive cosmological constraints. Lensed SNe are also powerful astrophysical probes. We review the usage of lensed SNe to constrain SN progenitors, acquire high-z SN spectra through lensing magnifications, infer SN sizes via microlensing, and measure properties of dust in galaxies. The current challenge in the field is the rarity and difficulty in finding lensed SNe. We describe various methods and ongoing efforts to find these spectacular explosions, forecast the properties of the expected sample of lensed SNe from upcoming surveys particularly the LSST, and summarize the observational follow-up requirements to enable the various scientific studies. We anticipate the upcoming years to be exciting with a boom in lensed SN discoveries.

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S. Suyu, A. Goobar, T. Collett, et. al.
Fri, 20 Jan 23
70/72

Comments: 48 pages, 18 figures; to be submitted to Space Science Reviews, Topical Collection “Strong Gravitational Lensing”, eds. J. Wambsganss et al

On the galaxy 3-point correlation function in Modified Gravity [CEA]

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http://arxiv.org/abs/2301.07240


The next generation of galaxy surveys will provide highly accurate measurements of the large-scale structure of the Universe, allowing for more stringent tests of gravity on cosmological scales. Higher order statistics are a valuable tool to study the non-Gaussianities in the matter field and to break degeneracies between modified gravity and other physical or nuisance parameters. However, understanding from first principles the behaviour of these correlations is essential to characterise deviations from General Relativity (GR), and the purpose of this work. This work uses contemporary ideas of Standard Perturbation Theory on biased tracers to characterize the three point correlation function (3PCF) at tree level for Modified Gravity models with a scale-dependent gravitational strength, and applies the theory to two specific models ($f(R)$ and DGP) that are representative for Chameleon and Vainshtein screening mechanisms. Additionally, we use a multipole decomposition, which apart from speeding up the algorithm to extract the signal from data, also helps to visualize and characterize GR deviations.

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A. Aviles and G. Niz
Thu, 19 Jan 23
13/100

Comments: 25 pages, 5 figures

Eddington accreting Black Holes in the Epoch of Reionization [CEA]

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http://arxiv.org/abs/2301.07129


The evolution of the luminosity function (LF) of Active Galactic Nuclei (AGNs) at $z \gtrsim 5$ represents a key constraint to understand their contribution to the ionizing photon budget necessary to trigger the last phase transition in the Universe, i.e. the epoch of Reionization. Recent searches for bright high-z AGNs suggest that the space densities of this population at $z>4$ has to be revised upwards, and sparks new questions about their evolutionary paths. Gas accretion is the key physical mechanism to understand both the distribution of luminous sources and the growth of central Super-Massive Black Holes (SMBHs). In this work, we model the high-z AGN-LF assuming that high-z luminous AGN shine at their Eddington limit: we derive the expected evolution as a function of the “duty-cycle” ($f_{\rm dc}$), i.e. the fraction of life-time that a given SMBH spends accreting at the Eddington rate. Our results show that intermediate values ($f_{\rm dc} \simeq 0.1$) predict the best agreement with the ionizing background and photoionization rate, but do not provide enough ionizing photons to account for the observed evolution of the hydrogen neutral fraction. Smaller values ($f_{\rm
dc} \lesssim 0.05$) are required for AGNs to be the dominant population responsible for Hydrogen reionization in the Early Universe. We then show that this low-$f_{\rm dc}$ evolution can be reconciled with the current constraints on Helium reionization, although it implies a relatively large number of inactive SMBHs at $z\gtrsim5$, in tension with SMBH growth models based on heavy seeding.

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F. Fontanot, S. Cristiani, A. Grazian, et. al.
Thu, 19 Jan 23
20/100

Comments: 11 pages, 5 figures, MNRAS accepted

A semi-model-independent approach to describe a cosmological database [CEA]

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http://arxiv.org/abs/2301.07369


A model-independent or non-parametric approach for modeling a database has been widely used in cosmology. In these scenarios, the data has been used directly to reconstruct an underlying function. In this work, we introduce a novel semi-model-independent method to do the task. The new approach not only removes some drawbacks of previous methods but also has some remarkable advantages. We combine the well-known Gaussian linear model with a neural network and introduce a procedure for the reconstruction of an arbitrary function. In the scenario, the neural network produces some arbitrary base functions which subsequently are fed to the Gaussian linear model. Given a prior distribution on the free parameters, the Gaussian linear model provides a close form for the posterior distribution as well as the Bayesian evidence. In addition, contrary to other methods, it is straightforward to compute the uncertainty.

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A. Mehrabi
Thu, 19 Jan 23
33/100

Comments: Comments welcome, See this https URL for the code

Enhanced curvature perturbations from spherical domain walls nucleated during inflation [CEA]

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http://arxiv.org/abs/2301.07230


We investigate spherical domain walls~(DWs) nucleated via quantum tunneling in multifield inflationary models and curvature perturbations induced by the inhomogeneous distribution of those DWs. We consider the case that the Euclidean action $S_{E}$ of DWs changes with time during inflation so that most of DWs nucleate when $S_{E}$ reaches the minimum value and the radii of DWs are almost the same. When the Hubble horizon scale exceeds the DW radius after inflation, DWs begin to annihilate and release their energy into background radiation. Because of the random nature of the nucleation process, the statistics of DWs is of the Poisson type and the power spectrum of curvature perturbations has a characteristic slope ${\cal P}{\cal R}(k)\propto k^{3}$. The amplitude of ${\cal P}{\cal R}(k)$ depends on the tension and abundance of DWs at the annihilation time while the peak mode depends on the mean separation of DWs. We also numerically obtain the energy spectra of scalar-induced gravitational waves from predicted curvature perturbations which are expected to be observed in multiband gravitational-wave detectors.

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Z. Zeng, J. Liu and Z. Guo
Thu, 19 Jan 23
48/100

Comments: N/A

Statistics of tidal and deformation eigenvalue fields in the primordial Gaussian matter distribution: the two-dimensional case [CEA]

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http://arxiv.org/abs/2301.07200


We study the statistical properties of the eigenvalues of the primordial tidal and deformation tensor for random Gaussian cosmic density fields. With the tidal and deformation tensors, Hessians of the gravitational and velocity potential, being Gaussian, the corresponding eigenvalue fields are distinctly non-Gaussian. Following the extension of the Doroshkevich formula for the joined distribution of eigenvalues to two-dimensional fields, we evaluate the two- and three-point correlation functions of the eigenvalue fields. In addition, we assess the number densities of singular points of the eigenvalue fields and find their corresponding two- and three-point correlation functions.
The role of tidal forces and the resulting mass element deformation in shaping the prominent anisotropic wall-like and filamentary components of the cosmic web has since long been recognized based on the Zel’dovich approximation. Less well-known is that the weblike spatial pattern is already recognizable in the primordial tidal and deformation eigenvalue field, even while the corresponding Gaussian density and the potential field appear merely as a spatially incoherent and unstructured random field. Furthermore, against the background of a full phase-space assessment of structure formation in the Universe, the caustic skeleton theory entails a fully analytical framework for the nonlinear evolution of the cosmic web. It describes the folding of the dark matter sheet and the emerging caustic singularities, fully specified by the deformation eigenvalues and eigenvectors. Finally, tidal tensor eigenvalues are of central importance, and understanding their distribution is critical in predicting the resulting rotation and orientation.
The current study applies to two-dimensional Gaussian random fields and will be generalized to a three-dimensional analysis in an upcoming study.

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J. Feldbrugge, Y. Yan and R. Weygaert
Thu, 19 Jan 23
68/100

Comments: 21 pages, 10 figures

Inflationary helical magnetic fields with a sawtooth coupling [CEA]

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http://arxiv.org/abs/2301.07699


We study the generation of helical magnetic fields during inflation by considering a model which does not suffer from strong coupling or large back-reaction. Electromagnetic conformal invariance is broken only during inflation by coupling the gauge-invariants $F_{\mu\nu}F^{\mu\nu}$ and $F_{\mu\nu}{\tilde{F}}^{\mu\nu}$ to a time-dependent function $I$ with a sharp transition during inflation. The magnetic power spectrum is scale-invariant up to the transition and very blue-shifted after that. The subsequent evolution of the helical magnetic field is subjected to magneto-hydrodynamical processes, resulting in far larger coherence lengths than those occurring after adiabatic decay. Scale-invariant quadratic gravity is a suitable framework to test the model, providing a natural physical interpretation. We show that fully helical magnetic fields are generated with values in agreement with the lower bounds on fields in the Intergalactic Medium derived from blazar observations. This model holds even at large/intermediate energy scales of inflation, contrary to what has been found in previous works.

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C. Cecchini and M. Rinaldi
Thu, 19 Jan 23
81/100

Comments: 23 pages, 3 figures. Comments are welcome!

Multifield Ultralight Dark Matter [CEA]

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http://arxiv.org/abs/2301.07114


Ultralight dark matter (ULDM) is usually taken to be a single scalar field. Here we explore the possibility that ULDM consists of $N$ light scalar fields with only gravitational interactions. This configuration is more consistent with the underlying particle physics motivations for these scenarios than a single ultralight field. ULDM halos have a characteristic granular structure that increases stellar velocity dispersion and can be used as observational constraints on ULDM models. In multifield simulations, we find that inside a halo the amplitude of the total density fluctuations decreases as $1/\sqrt{N}$ and that the fields do not become significantly correlated over cosmological timescales. Smoother halos heat stellar orbits less efficiently, reducing the velocity dispersion relative to the single field case and thus weakening the observational constraints on the field mass. Analytically, we show that for $N$ equal-mass fields with mass $m$ the ULDM contribution to the stellar velocity dispersion scales as $1/(N m^3)$. Lighter fields heat the most efficiently and if the smallest mass $m_L$ is significantly below the other field masses the dispersion scales as $1/(N^2 m_L^3)$.

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M. Gosenca, A. Eberhardt, Y. Wang, et. al.
Thu, 19 Jan 23
83/100

Comments: 11 pages, 7 figures, to be submitted to PRD

The Faraday Rotation Measure Grid of the LOFAR Two-metre Sky Survey: Data Release 2 [CEA]

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http://arxiv.org/abs/2301.07697


A Faraday rotation measure (RM) catalogue, or RM Grid, is a valuable resource for the study of cosmic magnetism. Using the second data release (DR2) from the LOFAR Two-metre Sky Survey (LoTSS), we have produced a catalogue of 2461 extragalactic high-precision RM values across 5720 deg$^{2}$ of sky (corresponding to a polarized source areal number density of $\sim$0.43 deg$^{-2}$). The linear polarization and RM properties were derived using RM synthesis from the Stokes $Q$ and $U$ channel images at an angular resolution of 20” across a frequency range of 120 to 168 MHz with a channel bandwidth of 97.6 kHz. The fraction of total intensity sources ($>1$ mJy beam$^{-1}$) found to be polarized was $\sim$0.2%. The median detection threshold was 0.6 mJy beam$^{-1}$ ($8\sigma_{QU}$), with a median RM uncertainty of 0.06 rad m$^{-2}$ (although a systematic uncertainty of up to 0.3 rad m$^{-2}$ is possible, after the ionosphere RM correction). The median degree of polarization of the detected sources is 1.8%, with a range of 0.05% to 31%. Comparisons with cm-wavelength RMs indicate minimal amounts of Faraday complexity in the LoTSS detections, making them ideal sources for RM Grid studies. Host galaxy identifications were obtained for 88% of the sources, along with redshifts for 79% (both photometric and spectroscopic), with the median redshift being 0.6. The focus of the current catalogue was on reliability rather than completeness, and we expect future versions of the LoTSS RM Grid to have a higher areal number density. In addition, 25 pulsars were identified, mainly through their high degrees of linear polarization.

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S. O’Sullivan, T. Shimwell, M. Hardcastle, et. al.
Thu, 19 Jan 23
87/100

Comments: 20 pages, 23 figures, 3 tables. Accepted for publication in MNRAS. Go to this https URL to download the catalogue and associated data products

Pushing the Limits of Detectability: Mixed Dark Matter from Strong Gravitational Lenses [CEA]

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http://arxiv.org/abs/2301.07265


One of the frontiers for advancing what is known about dark matter lies in using strong gravitational lenses to characterize the population of the smallest dark matter halos. There is a large volume of information in strong gravitational lens images — the question we seek to answer is to what extent we can refine this information. To this end, we forecast the detectability of a mixed warm and cold dark matter scenario using the anomalous flux ratio method from strong gravitational lensed images. The halo mass function of the mixed dark matter scenario is suppressed relative to cold dark matter but still predicts numerous low-mass dark matter halos relative to warm dark matter. Since the strong lens signal is a convolution over a range of dark matter halo masses and since the signal is sensitive to the specific configuration of dark matter halos, not just the halo mass function, degeneracies between different forms of suppression in the halo mass function, relative to cold dark matter, can arise. We find that, with a set of lenses with different configurations of the main deflector and hence different sensitivities to different mass ranges of the halo mass function, the different forms of suppression of the halo mass function between the warm dark matter model and the mixed dark matter model can be distinguished with $40$ lenses with Bayesian odds of 29.4:1.

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R. Keeley, A. Nierenberg, D. Gilman, et. al.
Thu, 19 Jan 23
88/100

Comments: 8 pages, 7 figures

Joint constraints on cosmological parameters using future multi-band gravitational wave standard siren observations [CEA]

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http://arxiv.org/abs/2301.06722


Gravitational waves (GWs) from the compact binary coalescences can be used as standard sirens to explore the cosmic expansion history. In the next decades, it is anticipated that we could obtain the multi-band GW standard siren data (from nanohertz to a few hundred hertz), which are expected to play an important role in cosmological parameter estimation. In this work, we give for the first time the joint constraints on cosmological parameters using the future multi-band GW standard siren observations. We simulate the multi-band GW standard sirens based on the SKA-era pulsar timing array (PTA), the Taiji observatory, and the Cosmic Explorer (CE) to perform cosmological analysis. In the $\Lambda$CDM model, we find that the joint PTA+Taiji+CE data could provide a tight constraint on the Hubble constant with a $0.5\%$ precision. Moreover, PTA+Taiji+CE could break the cosmological parameter degeneracies generated by CMB, especially in the dynamical dark energy models. When combining the PTA+Taiji+CE data with the CMB data, the constraint precisions of $\Omega_{\rm m}$ and $H_0$ are $1.0\%$ and $0.3\%$, meeting the standard of precision cosmology. The joint CMB+PTA+Taiji+CE data give $\sigma(w)=0.028$ in the $w$CDM model and $\sigma(w_0)=0.11$ and $\sigma(w_a)=0.32$ in the $w_0w_a$CDM model, which are comparable with or close to the latest constraint results by the CMB+BAO+SN. In conclusion, it is worth expecting to use the future multi-band GW observations to explore the nature of dark energy and measure the Hubble constant.

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S. Jin, S. Xing, Y. Shao, et. al.
Wed, 18 Jan 23
2/133

Comments: 10 pages, 5 figures

First Constraints on Growth Rate from Redshift-Space Ellipticity Correlations of SDSS Galaxies at $0.16 < z < 0.70$ [CEA]

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http://arxiv.org/abs/2301.06273


We report the first constraints on the growth rate of the universe, $f(z)\sigma_8(z)$, with intrinsic alignments (IA) of galaxies. We measure the galaxy density-intrinsic ellipticity cross-correlation and intrinsic ellipticity auto-correlation functions over $0.16 < z < 0.7$ from luminous red galaxies (LRG) and LOWZ and CMASS galaxy samples in the Sloan Digital Sky Survey (SDSS) and SDSS-III BOSS survey. We detect clear anisotropic signals of IA due to redshift-space distortions. By combining measured IA statistics with the conventional galaxy clustering statistics, we obtain tighter constraints on the growth rate. The improvement is particularly prominent for the LRG, which is the brightest galaxy sample and known to be strongly aligned with underlying dark matter distribution; we obtain $f\sigma_8 = 0.5297^{ + 0.0310}{ – 0.0316}$ (68\% C.L.) from the clustering-only analysis and $f\sigma_8 = 0.4871^{ + 0.0218}{ – 0.0222}$ with clustering and IA, meaning $24\%$ improvement. The constraint is in good agreement with the prediction of general relativity, $f\sigma_8 = 0.4937 $ at $z=0.34$. For LOWZ and CMASS samples, the improvement by adding the IA statistics is found to be $9\%$ and $2\%$, respectively. Our results indicate that the contribution from IA statistics for cosmological constraints can be further enhanced by carefully selecting galaxies for a shape sample.

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T. Okumura and A. Taruya
Wed, 18 Jan 23
6/133

Comments: 9 pages, 5 figures

Constraining minimally extended varying speed of light by cosmological chronometers [CEA]

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http://arxiv.org/abs/2301.06947


At least one dimensionless physical constant (i.e., a physically observable) must change for the cosmic time to make the varying speed of light (VSL) models phenomenologically feasible. Various physical constants and quantities also should be functions of cosmic time to satisfy all known local laws of physics, including special relativity, thermodynamics, and electromagnetism. Adiabaticity is another necessary condition to keep the homogeneity and isotropy of three-dimensional space [1]. To be a self-consistent theory, one should consider cosmic evolutions of physical constants and quantities when one derives Einstein’s field equations and their solutions. All these conditions are well satisfied in the so-called minimally extended varying speed of light (meVSL) model [2]. Unlike other VSL models, we show that the redshift-drift formula of the meVSL model is the same as standard model one. Therefore, we cannot use this as an experimental tool to verify the meVSL. Instead, one can still use the cosmological chronometers (CC) as a model-independent test of the meVSL. The current CC data cannot distinguish meVSL from the standard model (SM) when we adopt the best-fit present values of the Hubble parameter and matter density contrast from the Planck mission. However, the CC data prefer the meVSL when we choose Pantheon’s best-fit values of them.

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S. Lee
Wed, 18 Jan 23
15/133

Comments: 13 pages, 1 figure,. arXiv admin note: text overlap with arXiv:2011.09274

Estimating the feasibility of `standard speed-gun' distances [CEA]

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http://arxiv.org/abs/2301.06252


In a previous paper, we demonstrated a single-rung method for measuring cosmological distances in active galactic nuclei (AGN) that can be used from low redshift (z < 0.1) to high redshift (z > 3). This method relies on the assumption that the variability seen in AGN is constrained by the speed of light during a flare event and can therefore be used to estimate the size of an emitting region. A limitation of this method is that previously, the Doppler factor was required to be known. In this paper, we derive an extension of the `standard speed-gun’ method for measuring cosmological distances that depends on the maximum intrinsic brightness temperature that a source can reach, rather than the Doppler factor. If the precise value of the intrinsic brightness temperature does not evolve with redshift and flares are statistically independent, we can in principle improve the errors in measurements of the matter content of the universe (in a flat LambdaCDM model) statistically. We then explored how well a future observing program would constrain cosmological parameters. We found that recovering the input cosmology depends critically on the uncertainty of the intrinsic brightness temperature and the number of flares observed.

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J. Hodgson, B. L’Huillier, I. Liodakis, et. al.
Wed, 18 Jan 23
27/133

Comments: Accepted to MNRAS Letters

$H_0$ Tension in Torsion-based Modified Gravity [CEA]

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http://arxiv.org/abs/2301.06328


The rising concern in the Hubble constant tension ($H_0$ tension) of the cosmological models motivates the scientific community to search for alternative cosmological scenarios that could resolve the $H_0$ tension. In this regard, we aim to work on a torsion-based modified theory of gravity which is an alternative description to the coherence model. We find an analytic solution of the Hubble parameter using a linear Lagrangian function of torsion $T$ and trace of energy-momentum tensor $\mathcal{T}$ for the dust case. Further, we constrain the cosmological and model parameters; to do that, we use Hubble and Pantheon samples and Markov Chain Monte Carlo (MCMC) simulation through Bayesian statistics. We obtain the values of Hubble constant as $H_0= 69.9\pm 6.8$ km$s^{-1}$ Mp$c^{-1}$, $H_0= 70.3\pm 6.3$ km$s^{-1}$ Mp$c^{-1}$, and $H_0= 71.4\pm 6.3$ km$s^{-1}$ Mp$c^{-1}$ at confidence level (CL), for Hubble, Pantheon, and their combine analysis, respectively. These outputs of $H_0$ for our model align with the recent observational measurements of $H_0$. In addition, we test the $Om$ diagnostic to check our model’s dark energy profile.

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S. Mandal, S. Mishra and P. Sahoo
Wed, 18 Jan 23
28/133

Comments: Comments are welcome

Cosmological simulations of the same spiral galaxy: connecting the dark matter distribution of the host halo with the subgrid baryonic physics [CEA]

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http://arxiv.org/abs/2301.06189


The role of baryonic physics, star formation, and stellar feedback, in shaping the galaxies and their host halos is an evolving topic. The dark matter aspects are illustrated in this work by showing distribution features in a Milky-Way-sized halo. We focus on the halo morphology, geometry, and profile as well as the phase space distribution using one dark matter only and five hydrodynamical cosmological high-resolution simulations of the same halo with different subgrid prescriptions for the baryonic physics (Kennicut versus multi-freefall star formation and delayed cooling versus mechanical supernovae feedback). If some general properties like the relative halo-galaxy orientation are similar, the modifications of the gravitational potential due to the presence of baryons are found to induce different dark matter distributions (rounder and more concentrated halo). The mass density profile as well as the velocity distribution are modified distinctively according to the specific resulting baryonic distribution highlighting the variability of those properties (e.g inner power index from 1.3 to 1.8, broader speed distribution). The uncertainties on those features are of paramount importance for dark matter phenomenology, particularly when dealing with dark matter dynamics or direct and indirect detection searches. As a consequence, dark matter properties and prospects using cosmological simulations require improvement on baryonic physics description. Modeling such processes is a key issue not only for galaxy formation but also for dark matter investigations.

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A. Núñez-Castiñeyra, E. Nezri, P. Mollitor, et. al.
Wed, 18 Jan 23
38/133

Comments: N/A

High-fidelity reproduction of central galaxy joint distributions with Neural Networks [CEA]

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http://arxiv.org/abs/2301.06398


The relationship between galaxies and haloes is central to the description of galaxy formation, and a fundamental step towards extracting precise cosmological information from galaxy maps. However, this connection involves several complex processes that are interconnected. Machine Learning methods are flexible tools that can learn complex correlations between a large number of features, but are traditionally designed as deterministic estimators. In this work, we use the IllustrisTNG300-1 simulation and apply neural networks in a binning classification scheme to predict probability distributions of central galaxy properties, namely stellar mass, colour, specific star formation rate, and radius, using as input features the halo mass, concentration, spin, age, and the overdensity on a scale of 3 $h^{-1}$ Mpc. The model captures the intrinsic scatter in the relation between halo and galaxy properties, and can thus be used to quantify the uncertainties related to the stochasticity of the galaxy properties with respect to the halo properties. In particular, with our proposed method, one can define and accurately reproduce the properties of the different galaxy populations in great detail. We demonstrate the power of this tool by directly comparing traditional single-point estimators and the predicted joint probability distributions, and also by computing the power spectrum of a large number of tracers defined on the basis of the predicted colour-stellar mass diagram. We show that the neural networks reproduce clustering statistics of the individual galaxy populations with excellent precision and accuracy.

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N. Rodrigues, N. Santi, A. Montero-Dorta, et. al.
Wed, 18 Jan 23
40/133

Comments: 12 pages, 7 figures

Testing Linearly Coasting Cosmology by Strong Lensing System [CEA]

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http://arxiv.org/abs/2301.06714


The standard model of cosmology ($\Lambda$CDM) is facing a serious crisis caused by the inconsistencies in the measurements of some fundamental cosmological parameters (Hubble constant $H_{0}$ and cosmic curvature parameter $\Omega_{k}$ for example). On the other hand a strictly linear evolution of the cosmological scale factor is found to be an excellent fit to a host of observations. Any model that can support such a coasting presents itself as a falsifiable model as far as the cosmological tests are concerned. In this article the observational data of strong gravitational lensing (SGL) systems from SLACS, BELLS, LSD and SL2S surveys has been used to test the viability of linearly coasting cosmology. Assuming the spherically symmetric mass distribution in lensing galaxies, the ratio of angular diameter distance from lens to source and angular diameter distance of the source is evaluated and is used to constrain the power law cosmology. It is found that the linear coasting is consistent with the SGL data within 1-$\sigma$; in agreement with various independent studies.

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S. Gahlaut
Wed, 18 Jan 23
60/133

Comments: 12 pages, 2 figures

Towards $21$-cm intensity mapping at $z=2.28$ with uGMRT using the tapered gridded estimator II: Cross-polarization power spectrum [CEA]

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http://arxiv.org/abs/2301.06677


Neutral hydrogen ($\rm{HI}$) $21$-cm intensity mapping (IM) offers an efficient technique for mapping the large-scale structures in the universe. We introduce the ‘Cross’ Tapered Gridded Estimator (Cross TGE), which cross-correlates two cross-polarizations (RR and LL) to estimate the multi-frequency angular power spectrum (MAPS) $C_{\ell}(\Delta\nu)$. We expect this to mitigate several effects like noise bias, calibration errors etc., which affect the ‘Total’ TGE which combines the two polarizations. Here we apply the Cross TGE on a $24.4 \,\rm{MHz}$ bandwidth uGMRT Band $3$ data centred at $432.8 \,\rm{MHz}$ aiming $\rm{HI}$ IM at $z=2.28$. The measured $C_{\ell}(\Delta\nu)$ is modelled to yield maximum likelihood estimates of the foregrounds and the spherical power spectrum $P(k)$ in several $k$ bins. Considering the mean squared brightness temperature fluctuations, we report a $2\sigma$ upper limit $\Delta_{UL}^{2}(k) \le (58.67)^{2} \, {\rm mK}^{2}$ at $k=0.804 \, {\rm Mpc}^{-1}$ which is a factor of $5.2$ improvement on our previous estimate based on the Total TGE. Assuming that the $\rm{HI}$ traces the underlying matter distribution, we have modelled $C_{\ell}(\Delta\nu)$ to simultaneously estimate the foregrounds and $[\Omega_{\rm{HI}} b_{\rm{HI}}] $ where $\Omega_{\rm{HI}}$ and $b_{\rm{HI}}$ are the $\rm{HI}$ density and linear bias parameters respectively. We obtain a best fit value of $[\Omega_{\rm{HI}}b_{\rm{HI}}]^2 = 7.51\times 10^{-4} \pm 1.47\times 10^{-3}$ which is consistent with noise. Although the $2\sigma$ upper limit $[\Omega_{\rm{HI}}b_{\rm{HI}}]_{UL} \leq 0.061$ is $\sim 50$ times larger than the expected value, this is a considerable improvement over earlier works at this redshift.

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K. Elahi, S. Bharadwaj, A. Ghosh, et. al.
Wed, 18 Jan 23
63/133

Comments: 16 pages, 13 figures, accepted for publication in MNRAS

Constraining uber gravity with recent observations and elucidating the $H_0$ problem [CEA]

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http://arxiv.org/abs/2301.07044


This paper studies both $\Lambda$CDM and CDM models under the \”uber gravity theory, named \”u$\Lambda$CDM and \”uCDM respectively. We report bounds over their parameter phase-space using several cosmological data, in particular, the recent Pantheon+ sample. Based on the joint analysis, the best fit value of the \”uber characteristic parameter is $z_\oplus = 0.028^{+0.036}{-0.020}$ and $z\oplus = 0.960^{+0.031}_{-0.030}$ at 68\% confidence level for \”u$\Lambda$CDM and \”uCDM respectively. Furthermore, we find that the $\mathbb{H}0(z)$ diagnostic suggests the $H_0$ tension is not alleviated. Finally, both models are statistically compared with $\Lambda$CDM through the Akaike and Bayesian information criteria, which suggest that there is a modest evidence against for \”u$\Lambda$CDM, a strongest evidence for \”uCDM, against for the joint analysis, but both \”uber gravity models and $\Lambda$CDM are equally preferred for most of the single samples.

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G. Valdez, C. Quintanilla, M. García-Aspeitia, et. al.
Wed, 18 Jan 23
69/133

Comments: 9 pages, 4 figures

Investigating The Hubble Tension Through Hubble Parameter Data [CEA]

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http://arxiv.org/abs/2301.06140


The Hubble constant ($H_0$), which represents the expansion rate of the Universe, is one of the most important cosmological parameters. The recent measurements of $H_0$ using the distance ladder methods such as Type Ia Supernovae (SNe Ia) are significantly greater than the CMB measurements by Planck. The difference points to a crisis in the standard model of cosmology termed as Hubble tension.
In this work we compare different cosmological models, determine the Hubble constant and comment on the Hubble tension using the data from differential ages of galaxies. The data we use is free from the systematic effects as the absolute age estimation of the galaxies is not needed. We have used the Bayesian approach along with the commonly used maximum likelihood method to estimate $H_0$ and have calculated the AIC scores to compare the different cosmological models.The non-flat cosmological model provides a higher value for matter density as well as the Hubble constant compared to the flat $\Lambda$CDM model. The AIC score is smaller for the flat $\Lambda$CDM cosmology compared to the non-flat model indicating the flat model a better choice. The best-fit value of $H_0$ for both these models are $68.7\pm3.1$ km/s/Mpc and $72.2\pm4$ km/s/Mpc, respectively. Our results are consistent with the CCHP measurements. However, flat model result does not agree with the SH0ES result, while the non-flat result is inconsistent with the Planck value.

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R. Thakur, S. Gupta, R. Nigam, et. al.
Wed, 18 Jan 23
98/133

Comments: 9 pages, 2 figures

Solution of $H_0$ tension with evidence of dark sector interaction from 2D BAO measurements [CEA]

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http://arxiv.org/abs/2301.06097


We explore observational constraints on a cosmological model with an interaction between dark energy (DE) and dark matter (DM), using a compilation of 15 measurements of the 2D BAO (i.e., transversal) scale in combination with Planck-CMB data, to explore the parametric space of a class of interacting DE models. We find that 2D BAO measurements can generate different observational constraints compared to the traditional approach of studying the matter clustering in the 3D BAO measurements. The 2D BAO sample provides strong evidence in favor of the IDE model at more than 3$\sigma$. Also, contrary to the observations for the $\Lambda$CDM and IDE models when analyzed with Planck-CMB + 3D BAO data, we note that Planck-CMB + 2D BAO data favor high values of the Hubble constant $H_0$. From the joint analysis with Planck-CMB + 2D BAO + Gaussian prior on $H_0$, we find $H_0 = 73.4 \pm 0.88$ km/s/Mpc. Our results show that Planck-CMB + 2D BAO measurements form a minimal data set that solves the $H_0$ tension, and at the same time, it provides statistical evidence for the IDE cosmologies.

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A. Bernui, E. Valentino, W. Giarè, et. al.
Wed, 18 Jan 23
119/133

Comments: 7 Pages, 2 Figures, 2 Tables

Upcoming SKA precursor surveys and sensitivity to HI mass function [CEA]

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http://arxiv.org/abs/2301.06263


We describe a simulation for the distribution of galaxies focusing on the atomic Hydrogen content. We aim to make predictions for surveys of galaxies using the redshifted 21 cm line emission. We take the expected distribution of HI masses, circular velocities, sizes of galaxies and orientations into account for this simulation. We use the sensitivity of ASKAP and MeeKAT radio telescopes to estimate the number of detections of HI galaxies in upcoming surveys. We validate our simulation with earlier estimates carried out by using some of these considerations. We show that unlike earlier simulations that take some of the factors into account, the predicted number of galaxies and their distribution across masses changes significantly when all of these are accounted for. We describe our predictions for the MIGHTEE-HI and WALLABY surveys for blind detection of galaxies using the redshifted 21 cm radiation. We study the dependence of the predicted number of detections on the HI mass function. We also describe our future plans for improving the simulation.

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S. Bharti and J. Bagla
Wed, 18 Jan 23
123/133

Comments: 17 pages, 10 figures and 5 tables

The splashback radius of groups and clusters of galaxies at low redshifts [CEA]

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http://arxiv.org/abs/2301.05432


We present a study of the distribution of galaxies along the radius of 157 groups and clusters of galaxies (200~km~s$^{-1}$ < $\sigma$ < 1100~km~s$^{-1}$) of the local Universe (0.01 < $z$ < 0.1). We introduced a new boundary of galaxy systems and identified it with the splashback radius $R_{sp}$. We also identified the central region of galaxy systems with a radius of $R_c$. These radii are defined by the observed integrated distribution of the total number of galaxies depending on the squared distance from the center of the groups/clusters coinciding, as a rule, with the brightest galaxy. We show that the radius $R_{sp}$ is proportional to the $R_{200c}$ (radius of the virialized region of a galaxy cluster) and to the radius of the central region $R_c$ with a slope close to 1. Among the obtained dependences of the radii on X-ray luminosity, the $\log R_{sp}$ – $\log L_X$ relation has the lowest scatter. We measured $<R_{sp}>$ = $1.67\pm0.05$~Mpc for the total sample, $<R_{sp}>$ = $1.14\pm0.14$~Mpc for galaxy groups with $\sigma \leq$ 400~km~s$^{-1}$, $<R_{sp}>$ = $2.00\pm0.20$~Mpc for galaxy clusters with $\sigma$ > 400~km~s$^{-1}$. We found the average ratio of the radii $R_{sp}/R_{200c} = 1.40\pm0.02$ or $R_{sp}/R_{200m} = 0.88\pm0.02$.}

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F. Kopylova and A. Kopylov
Mon, 16 Jan 23
10/50

Comments: 7 pages, 3 figures, 1 table

Toward accurate measurement of property-dependent galaxy clustering: II. Tests of the smoothed density-corrected $V_{\rm max}$ method [CEA]

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http://arxiv.org/abs/2301.05520


We present a smoothed density-corrected $V_{\rm max}$ technique for building a random catalog for property-dependent galaxy clustering estimation. This approach is essentially based on the density-corrected $V_{\rm max}$ method of Cole(2011), with three improvements to the original method. To validate the improved method, we generate two sets of flux-limited samples from two independent mock catalogs with different $k+e$ corrections. By comparing the two-point correlation functions, our results demonstrate that the random catalog created by the smoothed density-corrected $V_{\rm max}$ approach provides a more accurate and precise measurement for both sets of mock samples than the commonly used $V_{\rm max}$ method and redshift shuffled method. For flux-limited samples and color-dependent subsamples, the accuracy of the projected correlation function is well constrained within $1\%$ on the scale $0.07 h^{-1}\rm Mpc$ to $30 h^{-1}\rm Mpc$. The accuracy of the redshift-space correlation function is less than $2\%$ as well. Currently, it is the only approach that holds promise for achieving the high-accuracy goal of clustering measures for next-generation surveys.

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L. Yang and Z. Li
Mon, 16 Jan 23
16/50

Comments: 19 pages, 12 figures. Accepted for publication in ApJ

Peculiar velocity effects on the Hubble constant from time-delay cosmography [CEA]

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http://arxiv.org/abs/2301.05574


Two major challenges of contemporary cosmology are the Hubble tension and the cosmic dipole tension. At the crossroad of these, we investigate the impact of peculiar velocities on estimations of the Hubble constant from time-delay cosmography. We quantify the bias on the inference of the Hubble constant due to peculiar velocities of the lens, the source and of the observer. The former two, which may cancel from one system to another, affect the determination of the angular diameter distances in the time-delay formula, and reconstructed quantities like the angle to the source, via a lens model. On the other hand, the peculiar velocity of the observer, which is a debated quantity in the context of the cosmic dipole tension, systematically affects observed angles through aberration, redshifts, angular diameter distance and reconstructed quantities. We compute in detail the effect of these peculiar velocities on the inference of the Hubble constant to linear order in the peculiar velocities for the seven lenses of the H0LiCOW/TDCOSMO collaboration. The bias generated by the observer’s peculiar velocity alone can reach $1.15\%$ for the lenses which are well aligned with it. This results in a $0.25 \%$ bias for the seven combined lenses. Assuming a typical peculiar velocity of $300$ km s$^{-1}$ for the lens and the source galaxies, these add an additional random uncertainty, which can reach $1\%$ for an individual lens, but reduces to $0.24\%$ for the full TDCOSMO sample. The picture may change if peculiar velocities turn out to be larger than expected. Any time-delay cosmography program which aims for percent precision on the Hubble constant may need to take this source of systematic bias into account. This is especially so for future ground-based surveys which cover a fraction of the celestial sphere that is well aligned with the observer’s peculiar velocity.

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C. Dalang, M. Millon and T. Baker
Mon, 16 Jan 23
17/50

Comments: 19 pages, 8 figures, 2 tables

Mapping the Universe with slitless spectroscopy [CEA]

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http://arxiv.org/abs/2301.05669


Euclid will survey most of the accessible extragalactic sky with imaging and slitless spectroscopy observations, creating a unique spectroscopic catalog of galaxies with H$\alpha$ line in emission that will map the Universe from $z=0.9$ to $1.8$. With low expected statistical errors, the error budget will likely be dominated by systematic errors related to uncertainties in the data and modelling. I will discuss the strategy that has been proposed to mitigate the expected systematic effects and propagate the uncertainty of mitigation to cosmological parameter errobars.

Read this paper on arXiv…

P. Monaco
Mon, 16 Jan 23
23/50

Comments: 4 pages, 2 figures, proceedings of the Hack100 conference, to appear on Memorie della Societa` Astronomica Italiana

Non-Gaussianity in the cosmic microwave background from loop quantum cosmology [CEA]

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http://arxiv.org/abs/2301.05406


Primordial non-Gaussianity has set strong constraints on models of the early universe. Studies have shown that Loop Quantum Cosmology (LQC), which is an attempt to extend inflationary scenario to planck scales, leads to a strongly scale dependent and oscillatory non-Gaussianity. In particular, the non-Gaussianity function $f_{_{\rm NL}}(k_1,\, k_2,\, k_3)$ generated in LQC, though similar to that generated during slow roll inflation at small scales, is highly scale dependent and oscillatory at large wavelengths. In this work, we investigate the imprints of such a primordial bispectrum in the bispectrum of Cosmic Microwave Background (CMB). Inspired by earlier works, we propose an analytical template for the primordial bispectrum in LQC and compute the corresponding reduced bispectra of temperature and electric polarisation and their three-point cross-correlations. We show that CMB bispectra generated in LQC is consistent with the observations from Planck. We conclude with a discussion of our results and its implications to LQC.

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R. K and V. Sreenath
Mon, 16 Jan 23
32/50

Comments: 17 pages, 8 figures

Modeling Strong Lenses from Wide-Field Ground-Based Observations in KiDS and GAMA [CEA]

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http://arxiv.org/abs/2301.05320


Despite the success of galaxy-scale strong gravitational lens studies with Hubble-quality imaging, the number of well-studied strong lenses remains small. As a result, robust comparisons of the lens models to theoretical predictions are difficult. This motivates our application of automated Bayesian lens modeling methods to observations from public data releases of overlapping large ground-based imaging and spectroscopic surveys: Kilo-Degree Survey (KiDS) and Galaxy and Mass Assembly (GAMA), respectively. We use the open-source lens modeling software PyAutoLens to perform our analysis. We demonstrate the feasibility of strong lens modeling with large-survey data at lower resolution as a complementary avenue to studies that utilize more time-consuming and expensive observations of individual lenses at higher resolution. We discuss advantages and challenges, with special consideration given to determining background source redshifts from single-aperture spectra and to disentangling foreground lens and background source light. High uncertainties in the best-fit parameters for the models due to the limits of optical resolution in ground-based observatories and the small sample size can be improved with future study. We give broadly applicable recommendations for future efforts, and with proper application this approach could yield measurements in the quantities needed for robust statistical inference.

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S. Knabel, B. Holwerda, J. Nightingale, et. al.
Mon, 16 Jan 23
37/50

Comments: 25 pages, 19 figures, accepted for publication in MNRAS following peer review

Debiasing Standard Siren Inference of the Hubble Constant with Marginal Neural Ratio Estimation [CEA]

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http://arxiv.org/abs/2301.05241


Gravitational wave (GW) standard sirens may resolve the Hubble tension, provided that standard siren inference of $H_0$ is free from systematic biases. However, standard sirens from binary neutron star (BNS) mergers suffer from two sources of systematic bias, one arising from the anisotropy of GW emission, and the other from the anisotropy of electromagnetic (EM) emission from the kilonova. For an observed sample of BNS mergers, the traditional Bayesian approach to debiasing involves the direct computation of the detection likelihood. This is infeasible for large samples of detected BNS merger due to the high dimensionality of the parameter space governing merger detection. In this study, we bypass this computation by fitting the Hubble constant to forward simulations of the observed GW and EM data under a simulation-based inference (SBI) framework using marginal neural ratio estimation. A key innovation of our method is the inclusion of BNS mergers which were only detected in GW, which allows for estimation of the bias introduced by EM anisotropy. Our method corrects for $\sim$90$\%$ of the bias in the inferred value of $H_0$ when telescope follow-up observations of BNS mergers have extensive tiling of the merger localization region, using known telescope sensitivities and assuming a model of kilonova emission. Our SBI-based method thus enables a debiased inference of the Hubble constant of BNS mergers, including both mergers with detected EM counterparts and those without.

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S. Gagnon-Hartman, J. Ruan and D. Haggard
Mon, 16 Jan 23
44/50

Comments: Accepted MNRAS, 14 pages, 10 figures

Strong gravitational lensing's `external shear' is not shear [CEA]

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http://arxiv.org/abs/2301.05244


The distribution of mass in galaxy-scale strong gravitational lenses is often modelled as an elliptical power law plus external shear', which notionally accounts for neighbouring galaxies and cosmic shear. We show that it does not. Except in a handful of rare systems, the best-fit values of external shear do not correlate with independent measurements of shear: from weak lensing in 45 Hubble Space Telescope images, or in 50 mock images of lenses with complex distributions of mass. Instead, the best-fit shear is aligned with the major or minor axis of 88% of lens galaxies; and the amplitude of the external shear increases if that galaxy is disky. We conclude thatexternal shear’ attached to a power law model is not physically meaningful, but a fudge to compensate for lack of model complexity. Since it biases other model parameters that are interpreted as physically meaningful in several science analyses (e.g. measuring galaxy evolution, dark matter physics or cosmological parameters), we recommend that future studies of galaxy-scale strong lensing should employ more flexible mass models.

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A. Etherington, J. Nightingale, R. Massey, et. al.
Mon, 16 Jan 23
47/50

Comments: 13 pages, 11 figures, submitted to MNRAS

Mapping the Universe with slitless spectroscopy [CEA]

Posted on by

http://arxiv.org/abs/2301.05669


Euclid will survey most of the accessible extragalactic sky with imaging and slitless spectroscopy observations, creating a unique spectroscopic catalog of galaxies with H$\alpha$ line in emission that will map the Universe from $z=0.9$ to $1.8$. With low expected statistical errors, the error budget will likely be dominated by systematic errors related to uncertainties in the data and modelling. I will discuss the strategy that has been proposed to mitigate the expected systematic effects and propagate the uncertainty of mitigation to cosmological parameter errobars.

Read this paper on arXiv…

P. Monaco
Mon, 16 Jan 23
1/50

Comments: 4 pages, 2 figures, proceedings of the Hack100 conference, to appear on Memorie della Societa` Astronomica Italiana

Peculiar velocity effects on the Hubble constant from time-delay cosmography [CEA]

Posted on by

http://arxiv.org/abs/2301.05574


Two major challenges of contemporary cosmology are the Hubble tension and the cosmic dipole tension. At the crossroad of these, we investigate the impact of peculiar velocities on estimations of the Hubble constant from time-delay cosmography. We quantify the bias on the inference of the Hubble constant due to peculiar velocities of the lens, the source and of the observer. The former two, which may cancel from one system to another, affect the determination of the angular diameter distances in the time-delay formula, and reconstructed quantities like the angle to the source, via a lens model. On the other hand, the peculiar velocity of the observer, which is a debated quantity in the context of the cosmic dipole tension, systematically affects observed angles through aberration, redshifts, angular diameter distance and reconstructed quantities. We compute in detail the effect of these peculiar velocities on the inference of the Hubble constant to linear order in the peculiar velocities for the seven lenses of the H0LiCOW/TDCOSMO collaboration. The bias generated by the observer’s peculiar velocity alone can reach $1.15\%$ for the lenses which are well aligned with it. This results in a $0.25 \%$ bias for the seven combined lenses. Assuming a typical peculiar velocity of $300$ km s$^{-1}$ for the lens and the source galaxies, these add an additional random uncertainty, which can reach $1\%$ for an individual lens, but reduces to $0.24\%$ for the full TDCOSMO sample. The picture may change if peculiar velocities turn out to be larger than expected. Any time-delay cosmography program which aims for percent precision on the Hubble constant may need to take this source of systematic bias into account. This is especially so for future ground-based surveys which cover a fraction of the celestial sphere that is well aligned with the observer’s peculiar velocity.

Read this paper on arXiv…

C. Dalang, M. Millon and T. Baker
Mon, 16 Jan 23
6/50

Comments: 19 pages, 8 figures, 2 tables

The splashback radius of groups and clusters of galaxies at low redshifts [CEA]

Posted on by

http://arxiv.org/abs/2301.05432


We present a study of the distribution of galaxies along the radius of 157 groups and clusters of galaxies (200~km~s$^{-1}$ < $\sigma$ < 1100~km~s$^{-1}$) of the local Universe (0.01 < $z$ < 0.1). We introduced a new boundary of galaxy systems and identified it with the splashback radius $R_{sp}$. We also identified the central region of galaxy systems with a radius of $R_c$. These radii are defined by the observed integrated distribution of the total number of galaxies depending on the squared distance from the center of the groups/clusters coinciding, as a rule, with the brightest galaxy. We show that the radius $R_{sp}$ is proportional to the $R_{200c}$ (radius of the virialized region of a galaxy cluster) and to the radius of the central region $R_c$ with a slope close to 1. Among the obtained dependences of the radii on X-ray luminosity, the $\log R_{sp}$ – $\log L_X$ relation has the lowest scatter. We measured $<R_{sp}>$ = $1.67\pm0.05$~Mpc for the total sample, $<R_{sp}>$ = $1.14\pm0.14$~Mpc for galaxy groups with $\sigma \leq$ 400~km~s$^{-1}$, $<R_{sp}>$ = $2.00\pm0.20$~Mpc for galaxy clusters with $\sigma$ > 400~km~s$^{-1}$. We found the average ratio of the radii $R_{sp}/R_{200c} = 1.40\pm0.02$ or $R_{sp}/R_{200m} = 0.88\pm0.02$.}

Read this paper on arXiv…

F. Kopylova and A. Kopylov
Mon, 16 Jan 23
12/50

Comments: 7 pages, 3 figures, 1 table

Debiasing Standard Siren Inference of the Hubble Constant with Marginal Neural Ratio Estimation [CEA]

Posted on by

http://arxiv.org/abs/2301.05241


Gravitational wave (GW) standard sirens may resolve the Hubble tension, provided that standard siren inference of $H_0$ is free from systematic biases. However, standard sirens from binary neutron star (BNS) mergers suffer from two sources of systematic bias, one arising from the anisotropy of GW emission, and the other from the anisotropy of electromagnetic (EM) emission from the kilonova. For an observed sample of BNS mergers, the traditional Bayesian approach to debiasing involves the direct computation of the detection likelihood. This is infeasible for large samples of detected BNS merger due to the high dimensionality of the parameter space governing merger detection. In this study, we bypass this computation by fitting the Hubble constant to forward simulations of the observed GW and EM data under a simulation-based inference (SBI) framework using marginal neural ratio estimation. A key innovation of our method is the inclusion of BNS mergers which were only detected in GW, which allows for estimation of the bias introduced by EM anisotropy. Our method corrects for $\sim$90$\%$ of the bias in the inferred value of $H_0$ when telescope follow-up observations of BNS mergers have extensive tiling of the merger localization region, using known telescope sensitivities and assuming a model of kilonova emission. Our SBI-based method thus enables a debiased inference of the Hubble constant of BNS mergers, including both mergers with detected EM counterparts and those without.

Read this paper on arXiv…

S. Gagnon-Hartman, J. Ruan and D. Haggard
Mon, 16 Jan 23
15/50

Comments: Accepted MNRAS, 14 pages, 10 figures

Non-Gaussianity in the cosmic microwave background from loop quantum cosmology [CEA]

Posted on by

http://arxiv.org/abs/2301.05406


Primordial non-Gaussianity has set strong constraints on models of the early universe. Studies have shown that Loop Quantum Cosmology (LQC), which is an attempt to extend inflationary scenario to planck scales, leads to a strongly scale dependent and oscillatory non-Gaussianity. In particular, the non-Gaussianity function $f_{_{\rm NL}}(k_1,\, k_2,\, k_3)$ generated in LQC, though similar to that generated during slow roll inflation at small scales, is highly scale dependent and oscillatory at large wavelengths. In this work, we investigate the imprints of such a primordial bispectrum in the bispectrum of Cosmic Microwave Background (CMB). Inspired by earlier works, we propose an analytical template for the primordial bispectrum in LQC and compute the corresponding reduced bispectra of temperature and electric polarisation and their three-point cross-correlations. We show that CMB bispectra generated in LQC is consistent with the observations from Planck. We conclude with a discussion of our results and its implications to LQC.

Read this paper on arXiv…

R. K and V. Sreenath
Mon, 16 Jan 23
41/50

Comments: 17 pages, 8 figures