Late-Time Dark Matter Oscillations and the Core-Cusp Problem

Abstract

The core-cusp problem persists as an unresolved tension between the predictions of $\Lambda$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 $m_{\chi }\sim (0.1-1)$ 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.

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

References in corpus (11)

• High-resolution mass models of dwarf galaxies from LITTLE THINGS
• Dwarf galaxies in CDM and SIDM with baryons: observational probes of the nature of dark matter
• Velocity-dependent Self-interacting Dark Matter from Groups and Clusters of Galaxies
• Diversity of dark matter density profiles in the Galactic dwarf spheroidal satellites
• Hidden Sector Hydrogen as Dark Matter: Small-scale Structure Formation Predictions and the Importance of Hyperfine Interactions
• Cosmic particle colliders: simulations of self-interacting dark matter with anisotropic scattering
• The surprising accuracy of isothermal Jeans modelling of self-interacting dark matter density profiles
• Warm Decaying Dark Matter and the Hubble Tension
• Probing Dark Matter Self-interaction with Ultra-faint Dwarf Galaxies
• Maximally self-interacting dark matter: models and predictions
• Dark Matter Annihilation Feedback in cosmological simulations I: Code convergence and idealised halos

Cited by in corpus (3)

• The rapid onset of stellar bars in the baryon-dominated centers of disk galaxies
• Probing late-time annihilations of oscillating asymmetric dark matter via rotation curves of galaxies
• Constraints on energy scales from dark matter decay in a gauged $B-L$ model