An actively accreting massive black hole in the dwarf starburst galaxy Henize 2-10

TL;DR

This paper reports the discovery of an actively accreting massive black hole in the dwarf galaxy Henize 2-10, providing insights into black hole formation and growth in early universe-like conditions.

Contribution

It provides the first evidence of an actively accreting massive black hole in a nearby dwarf starburst galaxy, linking black hole growth to early galaxy evolution.

Findings

Henize 2-10 hosts a ~1 million solar mass black hole.

The galaxy shows simultaneous starburst activity and black hole accretion.

Black hole growth may occur before the formation of galaxy spheroids.

Abstract

Supermassive black holes are now thought to lie at the heart of every giant galaxy with a spheroidal component, including our own Milky Way. The birth and growth of the first 'seed' black holes in the earlier Universe, however, is observationally unconstrained and we are only beginning to piece together a scenario for their subsequent evolution. Here we report that the nearby dwarf starburst galaxy Henize 2-10 contains a compact radio source at the dynamical centre of the galaxy that is spatially coincident with a hard X-ray source. From these observations, we conclude that Henize 2-10 harbours an actively accreting central black hole with a mass of approximately one million solar masses. This nearby dwarf galaxy, simultaneoulsy hosting a massive black hole and an extreme burst of star formation, is analogous in many ways to galaxies in the infant Universe during the early stages of black-hole growth and galaxy mass assembly. Our results confirm that nearby star-forming dwarf galaxies can indeed form massive black holes, and that by implication so can their primordial counterparts. Moreover, the lack of a substantial spheroidal component in Henize 2-10 indicates that supermassive black-hole growth may precede the build-up of galaxy spheroids.