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Title: Ultracompact Minihalos as Probes of Inflationary Cosmology

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 117; Journal Issue: 14; Related Information: CHORUS Timestamp: 2016-09-28 18:09:34; Journal ID: ISSN 0031-9007
American Physical Society
Country of Publication:
United States

Citation Formats

Aslanyan, Grigor, Price, Layne C., Adams, Jenni, Bringmann, Torsten, Clark, Hamish A., Easther, Richard, Lewis, Geraint F., and Scott, Pat. Ultracompact Minihalos as Probes of Inflationary Cosmology. United States: N. p., 2016. Web. doi:10.1103/PhysRevLett.117.141102.
Aslanyan, Grigor, Price, Layne C., Adams, Jenni, Bringmann, Torsten, Clark, Hamish A., Easther, Richard, Lewis, Geraint F., & Scott, Pat. Ultracompact Minihalos as Probes of Inflationary Cosmology. United States. doi:10.1103/PhysRevLett.117.141102.
Aslanyan, Grigor, Price, Layne C., Adams, Jenni, Bringmann, Torsten, Clark, Hamish A., Easther, Richard, Lewis, Geraint F., and Scott, Pat. Wed . "Ultracompact Minihalos as Probes of Inflationary Cosmology". United States. doi:10.1103/PhysRevLett.117.141102.
title = {Ultracompact Minihalos as Probes of Inflationary Cosmology},
author = {Aslanyan, Grigor and Price, Layne C. and Adams, Jenni and Bringmann, Torsten and Clark, Hamish A. and Easther, Richard and Lewis, Geraint F. and Scott, Pat},
abstractNote = {},
doi = {10.1103/PhysRevLett.117.141102},
journal = {Physical Review Letters},
number = 14,
volume = 117,
place = {United States},
year = {Wed Sep 28 00:00:00 EDT 2016},
month = {Wed Sep 28 00:00:00 EDT 2016}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevLett.117.141102

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Cited by: 8works
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  • Ultracompact minihalos (UCMHs) are dense dark matter structures, which can form from large density perturbations shortly after matter-radiation equality. If dark matter is in the form of weakly interacting massive particles (WIMPs), then UCMHs may be detected via their gamma-ray emission. We investigate how the Fermi satellite could constrain the abundance of UCMHs and place limits on the power spectrum of the primordial curvature perturbation. Detection by Fermi would put a lower limit on the UCMH halo fraction. The smallest detectable halo fraction f{sub UCMH} > or approx. 10{sup -7} is for M{sub UCMH{approx}}10{sup 3}M{sub {center_dot}}. If gamma-ray emission frommore » UCMHs is not detected, an upper limit can be placed on the halo fraction. The bound is tightest f{sub UCMH} < or approx. 10{sup -5} for M{sub UCMH{approx}}10{sup 5}M{sub {center_dot}}. The resulting upper limit on the power spectrum of the primordial curvature perturbation in the event of nondetection is in the range P{sub R} < or approx. 10{sup -6.5}-10{sup -6} on scales k{approx}10{sup 1}-10{sup 6} Mpc{sup -1}. This is substantially tighter than the existing constraints from primordial black hole formation on these scales; however, it assumes that dark matter is in the form of WIMPs, and UCMHs are not disrupted during the formation of the Milky Way halo.« less
  • It has been proposed that ultracompact minihalos (UCMHs) might be formed in earlier epoch. If dark matter consists of Weakly Interacting Massive Particles (WIMPs), UCMHs can be treated as the γ-ray sources due to dark matter annihilation within them. In this paper, we investigate the contributions of UCMHs formed during three phase transitions (i.e., electroweak symmetry breaking, QCD confinement and e{sup +}e{sup −} annihilation) to the extragalactic γ-ray background. Moreover, we use the Fermi-LAT observation data of the extragalactic γ-ray background to get the constraints on the current abundance of UCMHs produced during these phase transitions. We also compare thesemore » results with those obtained from Cosmic Microwave Background (CMB) observations and find that the constraints from the Fermi-LAT are more stringent than those from CMB.« less
  • The existence of substructure in halos of annihilating dark matter would be expected to substantially boost the rate at which annihilation occurs. Ultracompact minihalos of dark matter (UCMHs) are one of the more extreme examples of this. The boosted annihilation can inject significant amounts of energy into the gas of a galaxy over its lifetime. Here we determine the impact of the boost factor from UCMH substructure on the heating of galactic gas in a Milky Way-type galaxy, by means of N-body simulation. If 1% of the dark matter exists as UCMHs, the corresponding boost factor can be of ordermore » 10{sup 5}. For reasonable values of the relevant parameters (annihilation cross section 3×10{sup −26} cm{sup 3} s{sup −1}, dark matter mass 100 GeV, 10% heating efficiency), we show that the presence of UCMHs at the 0.1% level would inject enough energy to eject significant amounts of gas from the halo, potentially preventing star formation within ∼1 kpc of the halo centre.« less
  • In principle, the tensor metric (gravity-wave) perturbations that arise in inflationary models can, beyond probing the underlying inflationary model, provide information about the Universe: ionization history, presence of a cosmological constant, and epoch of matter-radiation equality. Because tensor perturbations give rise to the anisotropy of the cosmic background radiation (CBR) solely through the Sachs-Wolfe effect we are able to calculate analytically their contribution to the variance of the multipole moments of the CBR temperature anisotropy. In so doing, we carefully take account of the effect of tensor perturbations that entered the Hubble radius during both the matter-dominated and radiation-dominated epochsmore » by means of a transfer function. (Previously, only those modes that entered during the matter era were properly taken into account.) The striking feature in the spectrum of multipole amplitudes is a dramatic falloff for [ital l][approx gt] [radical]1+[ital z][sub LSS] , where [ital z][sub LSS] is the redshift of the last-scattering surface, which depends upon the ionization history of the Universe. Finally, using our transfer function we provide a more precise formula for the energy density in stochastic gravitational waves from inflation, and, using the Cosmic Background Explorer Differential Microwave Radiometer (COBE DMR) quadrupole normalization, we express this energy density in terms of the tilt'' of the spectrum of tensor perturbations alone and show that it is unlikely that the stochastic background of gravity waves can be detected directly in the foreseeable future.« less
  • We present an N = 1 locally supersymmetric theory in which all constraints for a successful new inflationary-universe scenario are satisfied and the gravitino mass is on the order of the electroweak scale. Sufficient baryon asymmetry is generated and the overproduction of entropy due to gravitinos and/or coherent field oscillations (which is typical of supersymmetric models) is avoided.