The stellar remnants of high-redshift nuclear starburst discs: a potential origin for nuclear star clusters?
Abstract
Nuclear starburst discs (NSDs) are very compact star-forming regions in the centres 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 ∼ 1 when obscured accretion on to 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, ≈20 per cent of the NSD remnants have half-light radii ≲ 10 pc, consistent with NSCs hosted in both late- 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 ∼ 1 appear to be a promising origin for the ≫1 Gyr NSC population in early- and late-type galaxies with large SMBHs.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 2019
- DOI:
- 10.1093/mnras/stz598
- arXiv:
- arXiv:1902.10682
- Bibcode:
- 2019MNRAS.485.2935G
- Keywords:
-
- galaxies: active;
- galaxies: formation;
- galaxies: nuclei;
- galaxies: Seyfert;
- galaxies: star clusters: general;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 7 pages, 6 figures, accepted by MNRAS