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T: Fachverband Teilchenphysik

T 24: Theoretische Astroteilchenphysik und Kosmologie II

T 24.2: Vortrag

Donnerstag, 18. März 2010, 17:00–17:15, HG XV

Cold Dark Matter decoupling in the presence of Warm Dark Matter self-interaction energy density — •Rainer Stiele and Jürgen Schaffner-Bielich — Institut für Theoretische Physik, Ruprecht-Karls-Universität Heidelberg

We investigated a two component dark matter scenario: collisionless cold dark matter and self-interacting warm dark matter. The elastic warm dark matter self-interaction contributes an additional energy density that can dominate in the early universe. Hence, chemical cold dark matter decoupling can occure in a so-called self-interaction dominated era, instead of the standard assumption of radiation domination.

In this talk we present our results on the properties of thermal cold dark matter relics for decoupling in a self-interaction dominated universe. We find that the natural scale of the collisionless cold dark matter annihilation cross-section depends linearly on the cold dark matter particle mass and exceeds the weak scale. This casts new light on the so-called ‘WIMP miracle’ and interestingly enough, such boosted cold dark matter annihilation cross-sections are able to explain the high energy cosmic-ray electron-plus-positron spectrum measured by Fermi-LAT and the excess in the PAMELA data on the positron fraction. We use the unitary bound and neutrino induced constraints on the dark matter annihilation cross-section to extract allowed combinations of dark matter particle parameters and elastic warm dark matter self-interaction strengths.