Primordial black holes capture by stars and induced collapse to low-mass stellar black holes

ABSTRACT Primordial black holes in the asteroid-mass window, which might constitute all dark matter, can be captured by stars when they traverse them at low enough velocity. After being placed on a bound orbit during star formation, repeatedly cross if happens to highly eccentric, slow down dynamical friction, and end up stellar core. The rate of these captures is highest haloes high matter density velocity dispersion, first form redshift z ∼ 20. We compute this capture for low-metallicity 0.3–$1\, {\rm M_{\odot }}$, find that fraction formed dwarf galaxies would primordial hole, then grow accretion mass may close total mass. show does not depend their over should much affected external tidal perturbations. These low-mass could discovered today low-metallicity, old binary systems Milky Way containing surviving main-sequence or white dwarf, via gravitational waves emitted merger with another compact object. No mechanisms standard evolution theory are known below Chandrasekhar mass, so detecting hole fundamentally impact our understanding evolution, early Universe.