Perturbing the accretion flow onto a supermassive black hole by a passing star

TL;DR

This paper uses GRMHD simulations to study how passing stars in a nuclear star-cluster perturb the accretion flow onto a supermassive black hole, affecting accretion rates and plasma outflows.

Contribution

It introduces a detailed simulation approach to analyze the impact of stellar passages on black hole accretion flows, highlighting the dynamic interactions in dense nuclear environments.

Findings

Passing stars cause fluctuations in accretion rates.

Stellar passages induce outflowing plasma blobs.

Perturbations can significantly alter accretion dynamics.

Abstract

The close neighbourhood of a supermassive black hole contains not only accreting gas and dust, but also stellar-sized objects like stars, stellar-mass black holes, neutron stars, and dust-enshrouded objects that altogether form a dense nuclear star-cluster. These objects interact with the accreting medium and they perturb the otherwise quasi-stationary configuration of the accretion flow. We investigate how the passages of a star can influence the black hole gaseous environment with GRMHD 2D and 3D simulations. We focus on the changes in the accretion rate and the associated emergence of outflowing blobs of plasma.