Dark Spiky Primordial Black Holes

TL;DR

This paper investigates whether primordial black holes could explain dark matter density spikes observed near certain black hole binaries, challenging the stellar-collapse origin hypothesis.

Contribution

It proposes that primordial black holes might be the source of dark matter spikes, offering an alternative explanation to stellar-collapse black holes.

Findings

Primordial black holes can naturally form ultra-dense dark matter mini-spikes.

Stellar-collapse black holes are unlikely to develop such dark matter features.

The primordial origin hypothesis provides a plausible explanation for observed dark matter spikes.

Abstract

Recent observations of two nearby black hole low-mass X-ray binaries have suggested possible indication of dark matter density spikes. While the evidence is compelling, one issue with this interpretation is that light black holes formed from stellar collapse are not expected to form dark matter spikes, and so it is unclear how the stellar-mass black holes in these binaries could have acquired such features. Since primordial black holes are expected to form ultra-dense dark matter mini-spikes, in this article we explore the possibility of a primordial origin for these light black holes.