# The stellar remnants of high redshift nuclear starburst discs: a potential origin for nuclear star clusters?

## TL;DR

This study models the stellar remnants of nuclear starburst discs at low redshift, suggesting they could be the origins of nuclear star clusters observed in galaxies today, especially those with large supermassive black holes.

## Contribution

It provides a detailed comparison of simulated stellar remnants of NSDs with observed nuclear star clusters, supporting the hypothesis that NSDs at high redshift are progenitors of present-day NSCs.

## Key findings

- Good match between simulated and observed NSC properties.
- Approximately 20% of remnants have sizes consistent with observed NSCs.
- Remnants follow similar size-luminosity relations as observed in nearby NSCs.

## Abstract

Nuclear starburst discs (NSDs) are very compact star-forming regions in the centers of galaxies that have been studied as a possible origin for the absorbing gas around a central active galactic nucleus. NSDs may be most relevant at $z\sim 1$ when obscured accretion onto supermassive black holes (SMBHs) is common. This paper describes the characteristics of the stellar remnants of NSDs at $z=0.01$, taking into account the evolution from $z=1$. Using a stellar synthesis model, the colours, masses, and luminosities of the stellar remnants are computed for a suite of 192 two-dimensional NSD models. These properties are compared to observations of local nuclear star clusters (NSCs), and a good match is found between the predicted and observed properties. Dynamical effects will likely cause the final remnant to be a rotating, nearly spherical distribution. In addition, $\approx 20$% of the NSD remnants have half-light radii <~ 10 pc, consistent with NSCs hosted in both late-type and early-type galaxies, and all the remnants follow similar size-luminosity relationships as observed in nearby NSCs. NSDs require the presence of a central SMBH and the most massive and compact stellar remnants are associated with the most massive SMBHs, although stellar clusters with a variety of sizes can be produced by all considered SMBH masses. Overall, NSDs at $z\sim 1$ appear to be a promising origin for the $\gg 1$ Gyr NSC population in early- and late-type galaxies with large SMBHs.