Constraints on Scalar Asymmetric Dark Matter from Black Hole Formation in Neutron Stars

TL;DR

This paper investigates how scalar asymmetric dark matter can accumulate in neutron stars, potentially forming black holes, and derives constraints on dark matter properties based on astrophysical observations, especially considering effects like Hawking radiation.

Contribution

It provides new constraints on scalar asymmetric dark matter properties from neutron star observations, accounting for Bose-Einstein condensation and Hawking radiation effects.

Findings

Constraints on scattering cross-section range from 10^{-45} to 10^{-52} cm^2.

For 1 GeV to 1 TeV mass range, constraints are below direct detection sensitivity.

Black hole formation in neutron stars imposes significant limits on scalar ADM.

Abstract

We consider possibly observable effects of asymmetric dark matter (ADM) in neutron stars. Since dark matter does not self-annihilate in the ADM scenario, dark matter accumulates in neutron stars, eventually reaching the Chandrasekhar limit and forming a black hole. We focus on the case of scalar ADM, where the constraints from Bose-Einstein condensation and subsequent black hole formation are most severe due to the absence of Fermi degeneracy pressure. We also note that in some portions of this constrained parameter space, non-trivial effects from Hawking radiation can modify our limits. We find that for scalar ADM with mass between 100 keV and 10^5 GeV, the constraint from pulsars in globular clusters on the scattering cross-section with neutrons ranges from \sigma_n < 10^{-45} cm^2 to 10^{-52} cm}^2. In particular, for scalar ADM with mass between 1 GeV and 1 TeV (in the case where black hole evaporation due to Hawking radiation is unimportant), the constraint on the scattering cross-section is below what is reachable with ton scale direct detection experiments.