# Constraining primordial black holes in dark matter with kinematics of dwarf galaxies

## TL;DR

This paper uses dwarf galaxy kinematics to place stringent constraints on the abundance of primordial black holes in dark matter, especially around stellar to intermediate mass scales, impacting theories of gravitational wave origins.

## Contribution

It introduces a novel method linking dwarf galaxy velocity dispersions to primordial black hole abundance, providing the tightest constraints to date in certain mass ranges.

## Key findings

- Primordial black hole fraction $f_{PBH}$ is constrained to be less than approximately 2.0×(1 M☉/m_PBH)^2 at 99.99% confidence.
- The method sets the most stringent limits on PBH abundance for masses between 1 and 1000 solar masses.
- Results challenge the primordial black hole origin hypothesis for some gravitational wave events.

## Abstract

We propose that the kinematical observations of dwarf galaxies can be used to constrain the primordial black hole's (PBH) abundance in dark matter since the presence of primordial black holes in star clusters will lead to the radial velocity dispersion of the system. For instance, using the velocity dispersion observations from Leo I we show that the primordial black hole fraction $f_{\rm PBH}\gtrsim 2.0\times(1~M_{\odot}/m_{\rm PBH})^2$ is ruled out at a 99.99\% confidence level. This method yields the most stringent limits on the PBH abundance at the mass scales $\sim (1-10^3)~M_{\odot}$ and tightly constrains the primordial origin of gravitational wave events observed by the LIGO experiments.