Toward Black Hole Stars: supermassive black hole growth in nuclear clusters via stellar-object and gas accretion

TL;DR

This paper explores a model where supermassive black holes grow through mergers and accretion in nuclear star clusters, predicting high tidal disruption event rates and dense galactic nuclei with black hole stars.

Contribution

It introduces a novel model linking SMBH growth to stellar-object and gas accretion, predicting observable high-redshift tidal disruption events and dense nuclear structures.

Findings

Higher predicted tidal disruption event rates at high redshift.

Formation of dense gas cocoons around central black hole stars.

Galactic nuclei with comparable masses in gas, stars, and black holes.

Abstract

Supermassive black hole (SMBH) growth plausibly occurs via runaway astrophysical black hole mergers in nuclear star clusters that form intermediate mass black hole seeds at high redshifts. Such a model yields an order-of-magnitude higher rate of tidal disruption events than that of compact-object captures. Our prediction, normalized to our proposed resolution of SMBH seeding, yields detectable tidal disruption event rates at high redshift. The resulting dense gas cocoons generate compact galactic nuclei, each incorporating a central, massive, black hole star, with comparable masses in gas, stars, and massive black holes within a scale of around a parsec as inferred from the various Little Red Dot spectral signatures.