Constraints on primordial black holes as dark matter candidates from capture by neutron stars

TL;DR

This paper examines how the capture of primordial black holes by neutron stars can constrain their role as dark matter, especially in dense globular cluster environments, excluding certain mass ranges for PBHs as dominant dark matter components.

Contribution

It provides new constraints on primordial black holes as dark matter candidates based on neutron star observations and specific dense environment conditions.

Findings

PBHs in the mass range 3×10^{18} g to 10^{24} g are excluded as all dark matter in dense globular clusters.

At simulated DM densities (~2000 GeV/cm^3), less than 5% of dark matter can be PBHs in the specified mass range.

Neutron star observations in high-density environments place significant limits on PBH dark matter hypothesis.

Abstract

We investigate constraints on primordial black holes (PBHs) as dark matter candidates that arise from their capture by neutron stars (NSs). If a PBH is captured by a NS, the star is accreted onto the PBH and gets destroyed in a very short time. Thus, mere observations of NSs put limits on the abundance of PBHs. High DM densities and low velocities are required to constrain the fraction of PBHs in DM. Such conditions may be realized in the cores of globular clusters if the latter are of a primordial origin. Assuming that cores of globular clusters possess the DM densities exceeding several hundred GeV/cm$^3$ would imply that PBHs are excluded as comprising all of the dark matter in the mass range $3\times 10^{18} \text{g} \lesssim m_\text{BH}\lesssim 10^{24} \text{g}$. At the DM density of $2\times 10^3$ GeV/cm$^3$ that has been found in simulations in the corresponding models, less than 5% of the DM may consist of PBH for these PBH masses.