title: Low-mass black holes as the remnants of primordial black hole formation.
abstract: Bridging the gap between the approximately ten solar mass 'stellar mass' black holes and the 'supermassive' black holes of millions to billions of solar masses are the elusive 'intermediate-mass' black holes. Their discovery is key to understanding whether supermassive black holes can grow from stellar-mass black holes or whether a more exotic process accelerated their growth soon after the Big Bang. Currently, tentative evidence suggests that the progenitors of supermassive black holes were formed as ∼10(4)-10(5) M(⊙) black holes via the direct collapse of gas. Ongoing searches for intermediate-mass black holes at galaxy centres will help shed light on this formation mechanism.
authors.affiliation: Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA. ujgreene@astro.princeton.edu
authors.forename: Jenny E
authors.initials: JE
authors.lastname: Greene