Strong constraints on clustered primordial black holes as dark matter

TL;DR

This paper demonstrates that large initial clustering of primordial black holes actually worsens constraints on their viability as dark matter, contrary to previous suggestions that clustering could relax these limits.

Contribution

The study challenges the idea that initial clustering of primordial black holes relaxes dark matter constraints, showing instead that it makes them more stringent.

Findings

Large initial clustering strengthens constraints on primordial black hole dark matter.

Contrary to prior claims, clustering does not alleviate but exacerbates observational limits.

Results suggest primordial black holes are less viable as dark matter candidates with clustering considered.

Abstract

The idea of dark matter in the form of primordial black holes has seen a recent revival triggered by the LIGO detection of gravitational waves from binary black hole mergers. In this context, it has been argued that a large initial clustering of primordial black holes can help alleviate the strong constraints on this scenario. In this work, we show that on the contrary, with large initial clustering the problem is exacerbated and constraints on primordial black hole dark matter become overwhelmingly strong.