Planck 2015 constraints on spatially-flat dynamical dark energy models [CEA]

http://arxiv.org/abs/1802.05571


We determine constraints on spatially-flat tilted dynamical dark energy XCDM and $\phi$CDM inflation models by analyzing Planck 2015 cosmic microwave background (CMB) anisotropy data and baryon acoustic oscillation (BAO) distance measurements. XCDM is a simple and widely used but physically inconsistent parameterization of dynamical dark energy, while the $\phi$CDM model is a physically consistent one in which a scalar field $\phi$ with an inverse power-law potential energy density powers the currently accelerating cosmological expansion. Both these models have one additional parameter compared to standard $\Lambda$CDM and both better fit the TT + lowP + lensing + BAO data than does the standard tilted flat-$\Lambda$CDM model, with $\Delta \chi^2 = -1.26\ (-1.60)$ for the XCDM ($\phi$CDM) model relative to the $\Lambda$CDM model. While this is a 1.1$\sigma$ (1.3$\sigma$) improvement over standard $\Lambda$CDM and so not significant, dynamical dark energy models cannot be ruled out. In addition, both dynamical dark energy models reduce the tension between the Planck 2015 CMB anisotropy and the weak lensing $\sigma_8$ constraints.

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J. Ooba, B. Ratra and N. Sugiyama
Fri, 16 Feb 18
8/42

Comments: 9 pages, 12 figures, 3 tables. arXiv admin note: text overlap with arXiv:1712.08617

Strongly gravitational lensed SNe Ia as multi-messengers: Direct test of the Friedmann-Lemaître-Robertson-Walker metric [CEA]

http://arxiv.org/abs/1802.05532


We present a new idea of testing the validity of the Friedmann-Lema\^{\i}tre-Robertson-Walker metric, through the multiple measurements of galactic-scale strong gravitational lensing systems with type Ia supernova acting as background sources. Each individual lensing system will provides a model-independent measurement of the geometrical optics of the universe along the line of sight the SNe Ia located, which is independent of the matter content of the universe and the applicability of the Einstein equation. This will provide us the valuable possibility of directly measuring the FRW metric on cosmological scales. Moreover, our results show that LSST would produce robust constraints on the spacial curvature comparable to Planck 2014 results, with 500 strongly lensed SNe Ia observed in the future.

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J. Qi, S. Cao, M. Biesiada, et. al.
Fri, 16 Feb 18
11/42

Comments: N/A

Reinterpreting Low Frequency LIGO/Virgo Events as Magnified Stellar-Mass Black Holes at Cosmological Distances [CEA]

http://arxiv.org/abs/1802.05273


Gravitational waves can be focussed by the gravity of an intervening galaxy, just like light, thereby magnifying binary merging events in the far Universe. High magnification by galaxies is found to be responsible for the brightest sources detected in sky surveys, but the low angular resolution of LIGO/Virgo is insufficient to check this lensing possibility directly. Here we find that the first six binary black hole (BBH) merging events reported by LIGO/Virgo show clear evidence for lensing in the plane of observed mass and source distance. The four lowest frequency events follow an apparent locus in this plane, which we can reproduce by galaxy lensing, where the higher the magnification, the generally more distant the source so the wave train is stretched more by the Universal expansion, by factors of 2-4. This revises the reported BBH distances upwards by an order of magnitude, equal to the square root of the magnification. Furthermore, the reported black hole masses must be decreased by 2-4 to counter the larger stretch factor, since the orbital frequency is used to derive the black hole masses. This lowers the masses to 5-15 solar, well below the puzzlingly high values of 20-35 solar masses otherwise estimated, with the attraction of finding agreement in mass with black holes orbiting stars in our own Galaxy, thereby implying a stellar origin for the low frequency events in the far Universe. We also show that the other two BBH events of higher frequency detected by LIGO/VIRGO, lie well below the lensing locus, consistent with being nearby and unlensed. If this apparent division between local and distant lensed events is reinforced by new detections then the spins and masses of stellar black holes can be compared over a timespan of 10 billion years by LIGO/Virgo.

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T. Broadhurst, J. Diego and G. Smoot
Fri, 16 Feb 18
24/42

Comments: 16 pages, 3 figures

Constraining screened fifth forces with the electron magnetic moment [CL]

http://arxiv.org/abs/1802.05545


Chameleon and symmetron theories serve as archetypal models for how light scalar fields can couple to matter with gravitational strength or greater, yet evade the stringent constraints from classical tests of gravity on Earth and in the Solar System. In this work, we investigate how a precision measurement of the electron magnetic moment places meaningful constraints on both chameleons and symmetrons. Two effects are identified: First, virtual chameleons and symmetrons run in loops to generate quantum corrections to the intrinsic value of the magnetic moment; a common process widely considered in the literature for many beyond-the-Standard-Model scenarios. A second effect, however, is unique to scalar fields that exhibit screening. A scalar bubble-like profile forms inside the experimental vacuum chamber and exerts a fifth force on the electron, leading to a systematic shift in the experimental measurement. In quantifying this latter effect, we present a novel approach that combines analytic arguments and a small number of numerical simulations to solve for the bubble-like profile quickly for a large range of model parameters. Taken together, both effects yield interesting constraints in complementary regions of parameter space. While the constraints we obtain for the chameleon are largely uncompetitive with those in the existing literature, this still represents the tightest constraint achievable yet from an experiment not originally designed to search for fifth forces. We break more ground with the symmetron, for which our results exclude a large and previously unexplored region of parameter space. Central to this achievement are the quantum correction terms, which are able to constrain symmetrons with masses in the range $\mu \in [10^{-3.88},10^8]\,\text{eV}$, whereas other experiments have hitherto only been sensitive to one or two orders of magnitude at a time. [Abridged]

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P. Brax, A. Davis, B. Elder, et. al.
Fri, 16 Feb 18
35/42

Comments: 19 pages + appendices, 12 figures. Abstract abridged for arXiv submission

Weak Lensing of Intensity Mapping: the Cosmic Infrared Background [CEA]

http://arxiv.org/abs/1802.05706


Gravitational lensing deflects the paths of cosmic infrared background (CIB) photons, leaving a measurable imprint on CIB maps. The resulting statistical anisotropy can be used to reconstruct the matter distribution out to the redshifts of CIB sources. To this end, we generalize the CMB lensing quadratic estimator to any weakly non-Gaussian source field, by deriving the optimal lensing weights. We point out the additional noise and bias caused by the non-Gaussianity and the `self-lensing’ of the source field. We propose methods to reduce, subtract or model these non-Gaussianities. We show that CIB lensing should be detectable with Planck data, and detectable at high significance for future CMB experiments like CCAT-Prime. The CIB thus constitutes a new source image for lensing studies, providing constraints on the amplitude of structure at intermediate redshifts between galaxies and the CMB. CIB lensing measurements will also give valuable information on the star formation history in the universe, constraining CIB halo models beyond the CIB power spectrum. By laying out a detailed treatment of lens reconstruction from a weakly non-Gaussian source field, this work constitutes a stepping stone towards lens reconstruction from continuum or line intensity mapping data, such as the Lyman-alpha emission, absorption, and the 21cm radiation.

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E. Schaan, S. Ferraro and D. Spergel
Fri, 16 Feb 18
36/42

Comments: Comments welcome

Are Cold Dynamical Dark Energy Models Distinguishable in the Light of the Data? [CEA]

http://arxiv.org/abs/1802.05087


In this paper we obtain observational constraints on three dynamical cold dark energy models ,include PL , CPL and FSL, with most recent cosmological data and investigate their implication for structure formation, dark energy clustering and abundance of CMB local peaks. From the joint analysis of the CMB temperature power spectrum from observation of the Planck, SNIa light-curve, baryon acoustic oscillation, $f\sigma_8$ for large scale structure observations and the Hubble parameter, the PL model has the highest growth of matter density, $ \Delta_{m} $, and matter power spectrum, $ P(k) $, compared to $\Lambda$CDM and other models. For the CPL on the other hand, the structure formation is considerably suppressed while the FSL has behavior similar to standard model of cosmology. Studying the clustering of dark energy, $ \Delta_{DE}$, yields positive but small value with maximum of $ \Delta_{DE}\simeq10^{-3} $ at early time due to matter behaviour of the PL, while for the CPL and FSL cross $ \Delta_{DE}=0 $ several time which demonstrate void of dark energy with $ \Delta_{DE}\simeq-10^{-11} $ in certain periods of the history of dark energy evolution. Among these three models, the PL model demonstrate that is more compatible with $ f\sigma_{8} $ data. We also investigated a certain geometrical measure, namely the abundance of local maxima as a function of threshold for three DDE models and find that the method is potentially capable to discriminate between the models, especially far from mean threshold. The contribution of PL and CPL for late ISW are significant compared to cosmological constant and FSL model. The tension in the Hubble parameters is almost alleviated in the PL model.

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A. Ebrahimi, M. Monemzadeh and H. Moshafi
Thu, 15 Feb 18
4/48

Comments: N/A

A Multi-Wavelength Analysis of Annihilating Dark Matter as the Origin of the Gamma-Ray Emission from M31 [HEAP]

http://arxiv.org/abs/1802.05258


[Abridged] Indirect detection of dark matter (DM) by multi-wavelength astronomical observations provides a promising avenue for probing the particle nature of DM. In the case of DM consisting of Weakly-Interacting Massive Particles (WIMPs), self-annihilation ultimately produces observable products including $e^{\pm}$ pairs and gamma rays. The gamma rays can be detected directly, while the $e^{\pm}$ pairs can be detected by radio emission from synchrotron radiation or X-rays and soft gamma rays from inverse Compton scattering. An intriguing region to search for astrophysical signs of DM is the Galactic center (GC) of the Milky Way, due in part to an observed excess of gamma-rays that could be DM. A recent observation by the Fermi-LAT collaboration of a similar excess in the central region of the Andromeda galaxy (M31) leads us to explore the possibility of a DM-induced signal there as well. We use the RX-DMFIT tool to perform a multi-frequency analysis of potential DM annihilation emissions in M31. We consider WIMP models consistent with the GC excess and calculate the expected emission across the electromagnetic spectrum in comparison with available observational data from M31. We find that the particle models that best fit the M31 excess favor lower masses than the GC excess. The best fitting models are for a $b\bar{b}$ final state with $M_{\chi}=11$ GeV and $\left<\sigma v\right>=2.26\times 10^{-26}$ cm$^3$s$^{-1}$, as well as an evenly mixed $b\bar{b}/\tau^+\tau^-$ final state with $M_{\chi}=5.8$ GeV and $\left<\sigma v\right>=2.03\times 10^{-26}$ cm$^3$s$^{-1}$. For conservative estimates of the diffusion and magnetic field models the expected radio emissions appear to be in tension with currently available data in the central region of M31, although this constraint has a fairly strong dependence on the values chosen for parameters describing the magnetic field strength and geometry.

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A. McDaniel, T. Jeltema and S. Profumo
Thu, 15 Feb 18
7/48

Comments: 10 pages, 6 figures, 1 table