paper

Testing dark matter interactions with CMB spectral distortions

arXiv:2101.04070 · doi:10.1103/PhysRevD.103.043541

Abstract

Possible interactions of dark matter (DM) with Standard Model (SM) particles can be tested with spectral distortions (SDs) of the cosmic microwave background (CMB). In particular, a non-relativistic DM particle that scatters elastically with photons, electrons or nuclei imprints a negative chemical potential to the CMB spectrum. This article revisits the first study of this effect, with an accurate treatment of heat exchange between DM and SM particles. We show that the instantaneous-decoupling approximation made in the original study systematically and significantly underestimates the amplitude of SDs. As a consequence, we derive tighter upper bounds to the DM-SM elastic-scattering cross section for DM masses MeV, from the non-detection of -distortions by FIRAS. We also show that a future instrument like PIXIE, sensitive to , would be able to probe DM-SM cross sections much smaller than first forecasted, and orders of magnitude below current upper limits from CMB-anisotropy data, up to DM masses of GeV. Lastly, we study the sensitivity of SDs to the electric and magnetic dipole moments of the DM. Although SDs can place non-trivial constraints on these models, we find that even future SD experiments are unlikely to improve upon the best current bounds. This article is accompanied by the public code DMDIST, which allows one to compute CMB SDs for generic particle-DM models, specified by their cross sections for elastic scattering with and annihilation into SM particles.

13 pages + refs, 9 figures. DMDIST available at https://cosmo.nyu.edu/yacine/dmdist/dmdist.html

References in corpus (55)

Cited by in corpus (28)