The Effects of Dark Matter Annihilation on Cosmic Reionization

Abstract

We revisit the possibility of constraining the properties of dark matter (DM) by studying the epoch of cosmic reionization. Previous studies have shown that DM annihilation was unlikely to have provided a large fraction of the photons that ionized the universe, but instead played a subdominant role relative to stars and quasars. The DM, however, begins to efficiently annihilate with the formation of primordial microhalos at $z\sim 100-200$, much earlier than the formation of the first stars. Therefore, if DM annihilation ionized the universe at even the percent level over the interval $z\sim 20-100$, it can leave a significant imprint on the global optical depth, $\tau$. Moreover, we show that cosmic microwave background (CMB) polarization data and future 21 cm measurements will enable us to more directly probe the DM contribution to the optical depth. In order to compute the annihilation rate throughout the epoch of reionization, we adopt the latest results from structure formation studies and explore the impact of various free parameters on our results. We show that future measurements could make it possible to place constraints on the dark matter's annihilation cross section that are at a level comparable to those obtained from the observations of dwarf galaxies, cosmic ray measurements, and studies of recombination.

7 pages 5 figures

References in corpus (27)

• Planck 2015 results. XIII. Cosmological parameters
• CMB Constraints on WIMP Annihilation: Energy Absorption During the Recombination Epoch
• Evidence of patchy hydrogen reionization from an extreme Ly$\alpha$ trough below redshift six
• Cosmic Reionization after Planck: Could Quasars Do It All?
• A universal model for halo concentrations
• Weak Corrections are Relevant for Dark Matter Indirect Detection
• Indirect Dark Matter Signatures in the Cosmic Dark Ages II. Ionization, Heating and Photon Production from Arbitrary Energy Injections
• What mass are the smallest protohalos?
• Impact of dark matter decays and annihilations on reionization
• Cosmic Reionization On Computers I. Design and Calibration of Simulations
• The Darkest Hour Before Dawn: Contributions to Cosmic Reionization from Dark Matter Annihilation and Decay
• Constraints on Dark Matter annihilations from reionization and heating of the intergalactic gas
• The Effects of Dark Matter Decay and Annihilation on the High-Redshift 21 cm Background
• Hierarchical Formation of Dark Matter Halos and the Free Streaming Scale
• Eliminating the optical depth nuisance from the CMB with 21 cm cosmology
• Cosmic Reionization On Computers II. Reionization History and Its Back Reaction on Early Galaxies
• The Dependence of Subhalo Abundance on Halo Concentration
• The impact of dark matter decays and annihilations on the formation of the first structures
• Constraining DM through 21 cm observations
• How Dark Matter Reionized The Universe
• Intergalactic medium heating by dark matter
• Impact of Dark Matter Annihilation on the High-Redshift Intergalactic Medium
• Particle decay in the early universe: predictions for 21 cm
• Universal clustering of dark matter in phase space
• Future sensitivity of neutrino telescopes to dark matter annihilations from the cosmic diffuse neutrino signal
• Evolution of Low Mass Galactic Subhalos and Dependence on Concentration
• Energy dissipation of energetic electrons in the inhomogeneous intergalactic medium during the epoch of reionization

Cited by in corpus (3)

• Collider and Dark Matter Searches in the Inert Doublet Model from Peccei-Quinn Symmetry
• Signatures of metal-free star formation in Planck 2015 Polarization Data
• 21-cm Constraints on Dark Matter Annihilation after an Early Matter-Dominated Era