2019MNRAS.485.2935G

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.