On the fate of the matter reinserted within young nuclear stellar clusters

TL;DR

This study models the gas dynamics within young nuclear star clusters, revealing the formation of a thick, torus-like structure around the SMBH and a powerful wind that isolates the SMBH from external matter.

Contribution

It introduces a hydrodynamical model that includes stellar, black hole, and radiative effects to study gas evolution in nuclear star clusters.

Findings

A filamentary, clumpy torus forms around the SMBH.

The torus is Compton thick and covers a large sky fraction.

A strong wind develops, preventing external matter infall.

Abstract

This paper presents a hydrodynamical model describing the evolution of the gas reinserted by stars within a rotating young nuclear star cluster (NSC). We explicitly consider the impact of the stellar component to the flow by means of a uniform insertion of mass and energy within the stellar cluster. The model includes the gravity force of the stellar component and a central supermassive black hole (SMBH), and accounts for the heating from the central source of radiation and the radiative cooling of the thermalized gas. By using a set of parameters typical for NSCs and SMBHs in Seyfert galaxies our simulations show that a filamentary/clumpy structure is formed in the inner part of the cluster. This "torus" is Compton thick and covers a large fraction of the sky (as seen from the SMBH). In the outer parts of the cluster a powerful wind is produced, that inhibits the infall of matter from larger scales and thus the NSC-SMBH interplay occurs in isolation.