Accretion onto Stars in the Disks of Active Galactic Nuclei

TL;DR

This paper investigates how accretion onto stars within active galactic nuclei disks differs from traditional models, emphasizing the influence of tidal effects from supermassive black holes on stellar evolution and related phenomena.

Contribution

It extends previous models by analyzing the impact of tidal effects and black hole parameters on stellar evolution in AGN disks, highlighting factors affecting stellar outcomes and chemical enrichment.

Findings

Tidal effects from supermassive black holes significantly influence stellar evolution in AGN disks.

Results are robust against assumptions about radiative feedback on accretion.

Star fate depends on black hole distance and mass, affecting explosions, remnants, and chemical processes.

Abstract

Disks of gas accreting onto supermassive black holes are thought to power active galactic nuclei (AGN). Stars may form in gravitationally unstable regions of these disks, or may be captured from nuclear star clusters. Because of the dense gas environment, the evolution of such embedded stars can diverge dramatically from those in the interstellar medium. This work extends previous studies of stellar evolution in AGN disks by exploring a variety of ways that accretion onto stars in AGN disks may differ from Bondi accretion. We find that tidal effects from the supermassive black hole significantly alter the evolution of stars in AGN disks, and that our results do not depend critically on assumptions about radiative feedback on the accretion stream. Thus, in addition to depending on $\rho/c_s^3$, the fate of stars in AGN disks depends sensitively on the distance to and mass of the supermassive black hole. This affects where in the disk stellar explosions occur, where compact remnants form and potentially merge to produce gravitational waves, and where different types of chemical enrichment take place.