Constraints on primordial black holes from observation of stars in dwarf galaxies

TL;DR

This paper introduces a method to limit the abundance of primordial black holes in dwarf galaxies by analyzing their potential to destroy Sun-like stars, providing new constraints on dark matter composition.

Contribution

It presents a novel numerical approach to constrain PBH abundance based on star destruction in dwarf galaxies, especially in the mass range around 10^{20}g.

Findings

No more than 35% of dark matter can be PBHs in the mass range 10^{18} to a few times 10^{21}g for Triangulum II.

Constraints are highly sensitive to the parameter ξ, representing the fraction of stars destroyed.

Improved observational estimates of ξ could significantly tighten PBH abundance limits.

Abstract

We propose a way to constrain the primordial black hole (PBH) abundance in the range of PBH masses $m$ around $10^{20}$g based on their capture by Sun-like stars in dwarf galaxies, with subsequent star destruction. We calculate numerically the probability of a PBH capture by a star at the time of its formation in an environment typical of dwarf galaxies. Requiring that no more than a fraction $\xi$ of stars in a dwarf galaxy is destroyed by PBHs translates into an upper limit on the PBH abundance. For the parameters of Triangulum II and $\xi=0.5$, we find that no more than $\sim 35\%$ of dark matter can consist of PBHs in the mass range $10^{18} - \text{(a few)}\times 10^{21}$g. The constraints depend strongly on the parameter $\xi$ and may significantly improve if smaller values of $\xi$ are established from observations. An accurate determination of $\xi$ from dwarf galaxy modeling is thus of major importance.