Hunting for massive black holes in dwarf galaxies

Abstract

Despite traditional thinking, an appreciable population of massive black holes (that is, more massive than stellar-mass black holes) may be lurking in dwarf galaxies. Before the last decade, nearly all known massive black holes were in the nuclei of giant galaxies and the existence of massive black holes in dwarf galaxies was highly controversial. The field has now been transformed, with a growing community of researchers working on a variety of observational studies and theoretical models of dwarf galaxies hosting massive black holes. Work in this area not only is important for a holistic understanding of dwarf galaxy evolution and feedback, but also may just tell us how the first `seeds' of massive black holes formed in the early Universe. In this Perspective, I discuss the current state of the field as well as future prospects. I also present new insights on the demographics of nearby dwarf galaxies, which can be used to help constrain the black hole occupation/active fraction as a function of mass and dwarf galaxy type.