Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Updated CMB constraints on Dark Matter annihilation cross-sections

Silvia Galli, Fabio Iocco, Gianfranco Bertone, Alessandro Melchiorri

Abstract

The injection of secondary particles produced by Dark Matter (DM) annihilation at redshift 100<z<1000 affects the process of recombination, leaving an imprint on Cosmic Microwave Background (CMB) anisotropies. Here we provide a new assessment of the constraints set by CMB data on the mass and self-annihilation cross-section of DM particles. Our new analysis includes the most recent WMAP (7-year) and ACT data, as well as an improved treatment of the time-dependent coupling between the DM annihilation energy with the thermal gas. We show in particular that the improved measurement of the polarization signal places already stringent constraints on light DM particles, ruling out 'thermal' WIMPs with mass less then about 10 GeV.

Updated CMB constraints on Dark Matter annihilation cross-sections

Abstract

The injection of secondary particles produced by Dark Matter (DM) annihilation at redshift 100<z<1000 affects the process of recombination, leaving an imprint on Cosmic Microwave Background (CMB) anisotropies. Here we provide a new assessment of the constraints set by CMB data on the mass and self-annihilation cross-section of DM particles. Our new analysis includes the most recent WMAP (7-year) and ACT data, as well as an improved treatment of the time-dependent coupling between the DM annihilation energy with the thermal gas. We show in particular that the improved measurement of the polarization signal places already stringent constraints on light DM particles, ruling out 'thermal' WIMPs with mass less then about 10 GeV.

Paper Structure

This paper contains 6 sections, 1 equation, 1 figure, 2 tables.

Table of Contents

  1. Introduction.
  2. Annihilating DM and Recombination.
  3. Updated CMB constraints
  4. Implementing the redshift dependence of $f$.
  5. Discussion and Conclusions.
  6. Acknowledgments.

Figures (1)

  • Figure 1: Constraints on the cross section $<\sigma v>$ in function of the mass, obtained using a variable $f(z)$ for particles annihilating in muons ($x$ signs) and in electrons (diamonds) using WMAP7 data (red) and WMAP7+ACT data (black) at 95% c.l.. The exclusion shaded areas are obtained for interpolation of the WMAP7 + ACT data points for muons (dark shading) and electrons (light shading). The black solid line indicates the standard thermal cross-section $<\sigma v>=3\times 10^{-26}cm^3/s$.