White Noise from Dark Matter: 21 cm Observations of Early Baryon Collapse

Abstract

In concordance cosmology, dark matter density perturbations generated by inflation lead to nonlinear, virialized minihalos, into which baryons collapse at redshift $z\sim 20$. We survey here novel baryon evolution produced by a modification of the power spectrum from white noise density perturbations at scales below $k\sim 10h{Mpc}^{-1}$ (the smallest scales currently measured with the Lyman-$\alpha$ forest). Exotic dark matter dynamics, such as would arise from scalar dark matter with a late phase transition (similar to an axion, but with lower mass), create such an amplification of small scale power. The dark matter produced in such a phase transition collapses into minihalos, with a size given by the dark matter mass within the horizon at the phase transition. If the mass of the initial minihalos is larger than $\sim 10^{-3}{M}_{\odot }$, the modified power spectrum is found to cause widespread baryon collapse earlier than standard $\Lambda$CDM, leading to earlier gas heating. It also results in higher spin temperature of the baryons in the 21 cm line relative to $\Lambda$CDM at redshifts $z>20$ if the mass of the minihalo is larger than $1M_{\odot }$. It is estimated that experiments probing 21 cm radiation at high redshift will contribute a significant constraint on dark matter models of this type for initial minihalos larger than $\sim 10M_{\odot }$. Early experiments reaching to $z\approx 15$ will constrain minihalos down to $\sim 10^3{M}_{\odot }$.

arXiv comment8 pages, 9 figures

References in corpus (26)

• Observational evidence for self-interacting cold dark matter
• The 2dF Galaxy Redshift Survey: Power-spectrum analysis of the final dataset and cosmological implications
• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• Sterile Neutrinos as Dark Matter
• In the Beginning: The First Sources of Light and the Reionization of the Universe
• The Fourth Data Release of the Sloan Digital Sky Survey
• Observational constraints on Cosmic Reionization
• Sterile Neutrino Hot, Warm, and Cold Dark Matter
• The Lyman-alpha Forest Power Spectrum from the Sloan Digital Sky Survey
• Axion Miniclusters and Bose Stars
• MACHO Project Limits on Black Hole Dark Matter in the 1-30 Solar Mass Range
• Measuring the Small-Scale Power Spectrum of Cosmic Density Fluctuations Through 21 cm Tomography Prior to the Epoch of Structure Formation
• SuperWIMP Dark Matter Signals from the Early Universe
• Damping scales of neutralino cold dark matter
• Primordial Black Holes as Dark Matter: The Power Spectrum and Evaporation of Early Structures
• Toward Epoch of Reionization Measurements with Wide-Field Radio Observations
• The power spectrum of SUSY-CDM on sub-galactic scales
• Small-scale clumps in the galactic halo and dark matter annihilation
• Annihilating Cold Dark Matter
• Fast-Roll Inflation
• Power Spectrum Sensitivity and the Design of Epoch of Reionization Observatories
• Improving Foreground Subtraction in Statistical Observations of 21 cm Emission from the Epoch of Reionization
• Astrophysical Effects of Scalar Dark Matter Miniclusters
• Femtolensing and Picolensing by Axion Miniclusters
• Dark Matter Halos with Cores from Hierarchical Structure Formation
• Big Bang Nucleosynthesis and Active-Sterile Neutrino Mixing: Evidence for Maximal Mu Neutrino <-> Tau Neutrino Mixing in Super Kamiokande?

Cited by in corpus (3)

• CMB bounds on disk-accreting massive Primordial Black Holes
• Small-scale clumps of dark matter
• The 21 cm signal and the interplay between dark matter annihilations and astrophysical processes