Lunch talk on Apr. 8, 2025

Dark Matter Annihilation at Cosmic Dawn

Speaker: Liqiang Hou (NCSU)

Venue: SWIFAR Building 2111

Time: 12:45 PM, Tuesday, Apr. 8, 2025

Abstract: 

Dark matter annihilation has the potential to leave an imprint on the properties of the first luminous structures at Cosmic Dawn as well as the overall evolution of the intergalactic medium (IGM). In this work, we employ a semi-analytic method to model dark matter annihilation during Cosmic Dawn (approximately redshift z=20 to 40), examining potential modifications to IGM evolution as well as gas collapse, cooling, and star formation in mini-halos. Our analysis takes into account the effects of dark matter-baryon velocity offsets, utilizing the public 21cmvFAST code, and producing predictions for the 21cm global signal. In this talk, I will present key findings from our simplified model, highlighting how dark matter annihilation suppresses gas fractions in small halos and modifies molecular cooling, potentially enhancing or suppressing star formation depending on the dark matter model, redshift, and assumed velocity offsets. Our results emphasize the necessity of detailed simulations of exotic energy injection, especially as upcoming observational probes shed new light on reionization and early galaxy formation.

Report PPT:  SWIFAR_Liqiang Hou.pdf