Limits on Primordial Black Holes from M87

TL;DR

This paper proposes a method to constrain primordial black hole dark matter using gravitational lensing effects near M87's supermassive black hole, leveraging high-resolution EHT observations.

Contribution

It introduces a novel approach linking light deflection by primordial black holes in dark matter spikes to observational limits from EHT data.

Findings

Strong limits on primordial black hole mass fraction in certain ranges

Dependence of results on dark matter spike models

Highlights need for further high-resolution observations

Abstract

Primordial black holes in the solar mass range are a possibly significant component of dark matter. We show how an argument relating the deflection of light by such black holes in the density spike likely to exist around the M87 supermassive black hole, combined with the high resolution observations of the EHT collaboration, can lead to a strong limits on the primordial black hole mass fraction in an astrophysically relevant mass range. The results depend on the model assumed for the dark matter spike and suggest the interest of further understanding of such spikes as well as further high resolution observations on supermassive black holes.