Late-Time Dark Matter Oscillations and the Core-Cusp Problem
Abstract
The core-cusp problem persists as an unresolved tension between the predictions of CDM cosmology and observations of dark matter (DM) profiles in dwarf spheroidal and other galaxies. We present a novel scenario for converting cusps into cores through reactivation of DM annihilation in galaxies at late times. This can happen in asymmetric DM models when there is a very small DM-number violating mass term that causes oscillations between DM and its antiparticle. Using analytic methods as well as gravitational N-body simulations, we show that this mechanism can robustly eliminate cusps from galactic DM profiles for light fermionic DM of mass GeV and a lighter mediator into which the DM can annihilate. We identify regions of parameter space where annihilation of DM particles is more efficient than elastic scattering at reducing the inner density of the DM profile. Dark matter annihilation is therefore a qualitatively distinct alternative to the mechanism of elastic self-interacting dark matter for addressing the cusp-core problem.
Cite
@article{arxiv.2010.12583,
title = {Late-Time Dark Matter Oscillations and the Core-Cusp Problem},
author = {James M. Cline and Guillermo Gambini and Samuel D. McDermott and Matteo Puel},
journal= {arXiv preprint arXiv:2010.12583},
year = {2021}
}
Comments
27 pages, 12 figures; v2: 30 pages, added discussion on Boltzmann equation in galaxies, two plots and appendix D, updated CMB constraint on $\delta m$ and references, improved version with clarifications; v3: matched published version