Detection significance of Baryon Acoustic Oscillations peaks in galaxy and quasar clustering [CEA]

http://arxiv.org/abs/1802.07737


We compare our analysis of the Baryon Acoustic Oscillations (BAO) feature in the correlation functions of SDSS BOSS DR12 LOWZ and CMASS galaxy samples with the findings of arXiv:1509.06371v2. Using subsets of the data we obtain an empirical estimate of the errors on the correlation functions which are in agreement with the simulated errors of arXiv:1509.06371v2. We find that the significance of BAO detection is the quantity most sensitive to the choice of the fitting range with the CMASS value decreasing from 8{\sigma} to 5.3{\sigma} in some cases. Via an F-ratio test, we demonstrate that the A(s) nuisance parameters play a significant role when fitting CMASS and LOWZ correlation functions with the fiducial {\Lambda}CDM model. Although our measurements of DV are in reasonable agreement with those of arXiv:1509.06371v2, we note unexplained issues when fitting with their full covariance which may reduce their estimate of BAO peak significance. We extend our BAO analysis to higher redshifts by fitting to the weighted mean of 2QDESp, SDSS DR5 UNIFORM, 2QZ and 2SLAQ quasar correlation functions, obtaining a 7.7% measurement compared to 3.9% achieved by eBOSS DR14. The larger error on quasar correlation functions implies a smaller role for nuisance parameters in providing a good fit. Although the eBOSS BAO peak significance is only at the 1.4-2.8{\sigma} level, we demonstrate that high-redshift quasars play a vital role in “standard ruler” BAO cosmology.

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B. Ansarinejad and T. Shanks
Fri, 23 Feb 18
31/64

Comments: 20 pages, 20 figures, submitted to MNRAS

Light Primordial Exotic Compact Objects as All Dark Matter [CEA]

http://arxiv.org/abs/1802.07728


The radiation emitted by horizonless exotic compact objects (ECOs), such as wormholes, 2-2-holes, fuzzballs, gravastars, boson stars, collapsed polymers, superspinars etc., is expected to be strongly suppressed when compared to the radiation of black holes. If large primordial curvature fluctuations collapse into such objects instead of black holes, they do not evaporate or evaporate much slower than black holes and could thus constitute all of the dark matter with masses below $M < 10^{-16}M_\odot.$ We re-evaluate the relevant experimental constraints for light ECOs in this mass range and show that very large new parameter space down to ECO masses $M\sim 10\,{\rm TeV}$ opens up for light primordial dark matter. A new dedicated experimental program is needed to test this mass range of primordial dark matter.

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M. Raidal, S. Solodukhin, V. Vaskonen, et. al.
Fri, 23 Feb 18
40/64

Comments: 5 pages, 2 figures

Gravitational Waves from Binary Mergers of Sub-solar Mass Dark Black Holes [CEA]

http://arxiv.org/abs/1802.08206


We explore the possible spectrum of binary mergers of sub-solar mass black holes formed out of dark matter particles interacting via a dark electromagnetism. We estimate the properties of these dark black holes by assuming that their formation process is parallel to Population-III star formation; except that dark molecular cooling can yield smaller opacity limit. We estimate the binary coalescence rates for the Advanced LIGO and Einstein telescope, and find that scenarios compatible with all current constraints could produce dark black holes at rates high enough for detection by Advanced LIGO.

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S. Shandera, D. Jeong and H. Gebhardt
Fri, 23 Feb 18
53/64

Comments: 6 pages, 2 figures

Neutron stars exclude light dark baryons [CL]

http://arxiv.org/abs/1802.08244


Exotic new particles carrying baryon number and with mass of order the nucleon mass have been proposed for various reasons including baryogenesis, dark matter, mirror worlds, and the neutron lifetime puzzle. We show that the existence of neutron stars with mass greater than 0.7 $M_\odot$ places severe constraints on such particles, requiring them to be heavier than 1.2 GeV or to have strongly repulsive self-interactions.

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D. McKeen, A. Nelson, S. Reddy, et. al.
Fri, 23 Feb 18
62/64

Comments: 5 pages, 1 figure

Late-time magnetogenesis driven by ALP dark matter and dark photon [CL]

http://arxiv.org/abs/1802.07269


We propose a mechanism which generates primordial magnetic fields after the $e^+e^-$ annihilations. Our mechanism involves an ultra-light axion-like particle (ALP) which constitutes the dark matter, and a dark $U(1)X$ gauge boson introduced to bypass the obstacle placed by the conductivity of cosmic plasma. In our scheme, coherently oscillating ALP amplifies the dark photon field, and part of the amplified dark photon field is concurrently converted to the ordinary magnetic field through the ALP-induced magnetic mixing. For the relevant ALP mass range $10^{-21} {\rm eV}\lesssim m\phi\lesssim 10^{-17}{\rm eV}$, our mechanism can generate $B\sim 10^{-24} \,(m_\phi/10^{-17} {\rm eV})^{5/4}\,{\rm G}$ with a coherent length $\lambda \sim (m_\phi/10^{-17} {\rm eV})^{-1/2}$ kpc, which is large enough to provide a seed of the galactic magnetic fields. The mechanism also predicts a dark $U(1)X$ electromagnetic field $E_X \sim B_X\sim 10\,(m\phi/10^{-17}{\rm eV})^{-1/4}{\rm nG}$, which can result in interesting astrophysical/cosmological phenomena by inducing the mixings between the ALP, ordinary photon, and dark photon states.

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K. Choi, H. Kim and T. Sekiguchi
Thu, 22 Feb 18
13/60

Comments: 6 pages, 2 figures

Cubic Halo Bias in Eulerian and Lagrangian Space [CEA]

http://arxiv.org/abs/1802.07622


Predictions of the next-to-leading order, i.e. one-loop, halo power spectra depend on local and non-local bias parameters up to cubic order. The linear bias parameter can be estimated from the large scale limit of the halo-matter power spectrum, and the second order bias parameters from the large scale, tree-level, bispectrum. Cubic operators would naturally be quantified using the tree-level trispectrum. As the latter is computationally expensive, we extent the quadratic field method proposed in Schmittfull et al. 2014 to cubic fields in order to estimate cubic bias parameters. We cross-correlate a basis set of cubic bias operators with the halo field and express the result in terms of the cross-spectra of these operators in order to cancel cosmic variance. We obtain significant detections of local and non-local cubic bias parameters, which are partially in tension with predictions based on local Lagrangian bias schemes. We directly measure the Lagrangian bias parameters of the protohaloes associated with our halo sample and clearly detect a non-local quadratic term in Lagrangian space. We do not find a clear detection of non-local cubic Lagrangian terms for low mass bins, but there is some mild evidence for their presence for the highest mass bin. While the method presented here focuses on cubic bias parameters, the approach could also be applied to quantifications of cubic primordial non-Gaussianity.

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M. Abidi and T. Baldauf
Thu, 22 Feb 18
16/60

Comments: 37 pages, 16 figures, 4 tables; comments welcome

Stunted accretion growth of black holes by combined effect of the flow angular momentum and radiation feedback [GA]

http://arxiv.org/abs/1802.07264


Accretion on to seed black holes (BHs) is believed to play a crucial role in formation of supermassive BHs observed at high-redshift (z>6). Here, we investigate the combined effect of gas angular momentum and radiation feedback on the accretion flow, by performing 2D axially symmetric radiation hydrodynamics simulations that solve the flow structure across the Bondi radius and the outer part of the accretion disc simultaneously. The accreting gas with finite angular momentum forms a rotationally-supported disc inside the Bondi radius, where the accretion proceeds by the angular momentum transport due to assumed alpha-type viscosity. We find that the interplay of radiation and angular momentum significantly suppresses accretion even if the radiative feedback is weakened in an equatorial shadowing region. The accretion rate is O(alpha)\sim O(0.01-0.1) times the Bondi value, where alpha is the viscosity parameter. By developing an analytical model, we show that such a great reduction of the accretion rate persists unless the angular momentum is so small that the corresponding centrifugal radius is \lesssim 0.01 times the Bondi radius. We argue that BHs are hard to grow quickly via rapid mass accretion considering the angular momentum barrier presented in this paper.

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K. Sugimura, T. Hosokawa, H. Yajima, et. al.
Thu, 22 Feb 18
21/60

Comments: 16 pages, 12 figures, submitted to MNRAS