Speaker
Ms
Laura van den Aarssen
(Universität Hamburg)
Description
The expansion of the Universe causes DM annihilations to cease at chemical decoupling, but the DM is still kept in thermal equilibrium until kinetic decoupling. The temperature $T_{\text{kd}}$ at which this happens translates directly into a small-scale cutoff for the matter density fluctuations. After kinetic decoupling the WIMP temperature decreases more quickly than the heat bath temperature, which causes the DM to reenter an era of annihilation if the cross-section is enhanced by the Sommerfeld effect. This can influence the final relic abundance of the DM signifcantly. Important for this discussion is the velocity distribution of the WIMPs, which can be kept Maxwellian by DM self-scatterings, and the temperature at which the annihilations finally cease, either by matter domination or the saturation of the Sommerfeld factor. The temperatures at which these effects take place, and the total effect on the final relic density are estimated for a leptophilic model and an estimate for the cutoff mass $M_{\text{cutoff}}$ for the first protohalos will be given in this talk.
Primary author
Ms
Laura van den Aarssen
(Universität Hamburg)
Co-authors
Dr
Torsten Bringmann
(Universität Hamburg)
Mr
Yaşar Gödecke
(Universität Hamburg)
