Constraints on Bosonic Dark Matter From Observations of Old Neutron Stars

TL;DR

This paper examines how observations of old neutron stars constrain bosonic dark matter properties, especially considering self-interactions and annihilation, and finds that annihilating dark matter evades these constraints.

Contribution

It provides updated bounds on bosonic dark matter mass and interactions based on neutron star collapse, including effects of self-interactions and annihilation.

Findings

Bounds extend up to $m_X \\sim 10^{5-7}$ GeV for non-annihilating dark matter.

Constraints are ineffective for annihilating dark matter with high annihilation cross-section.

Dark matter decay does not significantly alter the bounds.

Abstract

Baryon interactions with bosonic dark matter are constrained by the potential for dark matter-rich neutron stars to collapse into black holes. We consider the effect of dark matter self-interactions and dark matter annihilation on these bounds, and treat the evolution of the black hole after formation. We show that, for non-annihilating dark matter, these bounds extend up to $m_X \sim 10^{5-7}$ GeV, depending on the strength of self-interactions. However, these bounds are completely unconstraining for annihilating bosonic dark matter with an annihilation cross-section of $<\sigma_a v> \gtrsim 10^{-38} {\rm cm^3 /s}$. Dark matter decay does not significantly affect these bounds. We thus show that bosonic dark matter accessible to near-future direct detection experiments must participate in an annihilation or self-interaction process to avoid black hole collapse constraints from very old neutron stars.