Evidence for Three Accreting Black Holes in a Galaxy at z~1.35: A Snapshot of Recently Formed Black Hole Seeds?

TL;DR

This study presents evidence of three actively accreting black holes in a galaxy at redshift 1.35, providing insights into black hole seed formation and galaxy evolution during this epoch.

Contribution

It reports the discovery of multiple black holes in a single galaxy at z=1.35, suggesting in-situ formation or merger scenarios relevant to seed models.

Findings

Detection of black holes with masses 10^6 - 10^7 Msun in a galaxy at z=1.35

Black holes may form in situ or via galaxy mergers

Implications for late black hole seed formation in star-forming galaxies

Abstract

One of the key open questions in cosmology today pertains to understanding when, where and how super massive black holes form, while it is clear that mergers likely play a significant role in the growth cycles of black holes, how supermassive black holes form, and how galaxies grow around them. Here, we present Hubble Space Telescope WFC3/IR grism observations of a clumpy galaxy at z=1.35, with evidence for 10^6 - 10^7 Msun rapidly growing black holes in separate sub-components of the host galaxy. These black holes could have been brought into close proximity as a consequence of a rare multiple galaxy merger or they could have formed in situ. Such holes would eventually merge into a central black hole as the stellar clumps/components presumably coalesce to form a galaxy bulge. If we are witnessing the in-situ formation of multiple black holes, their properties can inform seed formation models and raise the possibility that massive black holes can continue to emerge in star-forming galaxies as late as z=1.35 (4.8 Gyr after the Big Bang).