Updated CMB constraints on Dark Matter annihilation cross-sections

Understand

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.