Primordial black hole tower: Dark matter, earth-mass, and LIGO black holes

Abstract

We investigate a possibility of primordial black hole (PBH) formation with a hierarchical mass spectrum in multiple phases of inflation. As an example, we find that one can simultaneously realize a mass spectrum that has recently attracted a lot of attention: stellar-mass PBHs ($\ensuremath{\sim}\mathcal{O}(10)\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$) as a possible source of binary black holes detected by LIGO/Virgo collaboration, asteroid-mass ($\ensuremath{\sim}\mathcal{O}({10}^{\ensuremath{-}12})\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$) as a main component of dark matter, and earth-mass ($\ensuremath{\sim}\mathcal{O}({10}^{\ensuremath{-}5})\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$) as a source of ultrashort-timescale events in Optical Gravitational Lensing Experiment microlensing data. The recent refined de Sitter swampland conjecture may support such a multiphase inflationary scenario with hierarchical mass PBHs as a transition signal of each inflationary phase.