Constraint on the abundance of primordial black holes in dark matter from Planck data

TL;DR

This paper uses Planck 2015 data to set stringent constraints on primordial black holes as dark matter candidates, significantly improving previous limits and impacting gravitational wave event interpretations.

Contribution

It provides the first tight constraints on PBH abundance from Planck data under two reionization models, reducing previous upper limits by about two orders of magnitude.

Findings

Upper limits on PBH abundance are significantly improved.

Merger event rates for PBH binaries are constrained to be very low.

GW150914 is unlikely caused by PBH binary mergers.

Abstract

We use Planck data released in 2015 to constrain the abundance of primordial black holes (PBHs) in dark matter in two different reionization models (one is the instantaneous reionization and the other is the asymmetric reionization), and significantly improve the upper limits on the abundance of PBHs from WMAP 3-year data by around two orders of magnitude. Furthermore, these new limits imply that the event rates of mergers of PBH binaries (Gpc$^{-3}$ yr$^{-1}$) are less than $0.002$ for $M_\text{pbh}=30M_\odot$, $5$ for $M_\text{pbh}=10M_\odot$ and $2000$ for $M_\text{pbh}=2M_\odot$ at $95\%$ confidence level (C.L.), and thus GW150914 seems very unlikely produced by the merger of a PBH binary.