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

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.