Annihilation signals from asymmetric dark matter

Abstract

Abstract:In the simplest models of asymmetric dark matter (ADM) annihilation signals are not expected, since the DM is non-self-conjugate and the relic density of anti-DM is negligible. We investigate a new class of models in which a symmetric DM component, in the 'low-mass' 1-10 GeV regime favoured for linking the DM and baryon asymmetries, is repopulated through decays. We find that, in models without significant velocity dependence of the annihilation cross section, observational constraints generally force these decays to be (cosmologically) slow. These late decays can give rise to gamma-ray signal morphologies differing from usual annihilation profiles. A distinctive feature of such models is that signals may be absent from dwarf spheroidal galaxies.

Challenges in explaining the Galactic Center gamma-ray excess with millisecond pulsars

“…More specifically, this signal can be well fit by [31][32][33][34][35][36][37][38][39][40] GeV dark matter particles annihilating to bb with a cross section of σv = (1.7 − 2.3) × 10 −26 cm 3 /s (or by somewhat lighter particles annihilating to lighter quarks with a slightly lower cross section) [1]. The possibility that this signal constitutes the first detection of particle dark matter interactions has received considerable interest, and many dark matter models have been put forth as potentially viable explanations for the observed excess .…”

Interpretation of the gamma-ray excess and AMS-02 antiprotons: Velocity dependent dark matter annihilations

“…Meanwhile, the updated constraints of the dwarf spheroidal galaxies from the Fermi-LAT [16][17][18] seem in tension with most DM interpretations of the GC gamma-ray excess. Yet, some schemes can also be compatible with the constraints of dwarf galaxies, such as WIMPs annihilating into µ + µ − , e + e − [19,20], decays of the asymmetric DM with anti-DM holding enough energy to escape dwarf spheroidal galaxies [21], or the p-wave annihilating DM from a decaying predecessor [22]. Another possible explanation about the gamma-ray excess is the millisecond pulsars [2][3][4][23][24][25][26][27], while some discussions [28][29][30][31] indicate that this astrophysical explanation seems challenging to produce the majority of the observed gamma-ray excess.…”

Flavored dark matter and the Galactic Center gamma-ray excess

“…Thermal relic dark matter particles with a mass of [31][32][33][34][35][36][37][38][39][40] GeV and that dominantly annihilate to bottom quarks have been shown to provide an excellent description of the excess gamma rays observed from the center of the Milky Way. Flavored dark matter provides a well-motivated framework in which the dark matter can dominantly couple to bottom quarks in a flavor-safe manner.…”

“…For other investigations motivated by the gamma-ray excess, see Refs. [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42].…”