Constraints on primordial black holes from observation of stars in dwarf galaxies
Nicolas Esser, P. Tinyakov
Abstract
We propose a way to constrain the primordial black hole (PBH) abundance in the range of PBH masses $m$ around ${10}^{20}\text{ }\text{ }\mathrm{g}$ 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 $\ensuremath{\xi}$ 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 $\ensuremath{\xi}=0.5$, we find that no more than $\ensuremath{\sim}35%$ of dark matter can consist of PBHs in the mass range ${10}^{18}--(\text{a few})\ifmmode\times\else\texttimes\fi{}{10}^{21}\text{ }\text{ }\mathrm{g}$. The constraints depend strongly on the parameter $\ensuremath{\xi}$ and may significantly improve if smaller values of $\ensuremath{\xi}$ are established from observations. An accurate determination of $\ensuremath{\xi}$ from dwarf galaxy modeling is thus of major importance.