Chemical Evolution in Nuclear Stellar Discs

TL;DR

This paper models the chemical evolution of Nuclear Stellar Discs in barred galaxies, predicting abundance profiles under different gas accretion scenarios to aid interpretation of their unique chemical signatures.

Contribution

It introduces the first multizonal chemical evolution models for NSDs, enabling better understanding of their nucleosynthesis and accretion processes.

Findings

NSDs provide a unique environment to study chemical evolution.

Different accretion modes leave distinct abundance signatures.

Models can help interpret observational data of NSDs.

Abstract

Nuclear Stellar Discs (NSDs) have been observed in the vast majority of barred disc galaxies including the Milky Way. Their intense star formation is sustained by the intense gas inflows driven by their surrounding bars and frequently supports a large-scale galactic fountain. Despite their central role in galaxy evolution, their chemical evolution remains largely unexplored. We argue that the chemical composition of NSDs is best understood relative to the bar tips from which their gas is drawn. We make predictions of the detailed abundance profiles of gas and young stars within the NSD under different accretion scenarios from the galactic bar. We present the first systematic, multizonal modelling of the chemical evolution of nuclear stellar discs based on the RAMICES II code. We show that due to their different star formation history to galactic discs, NSDs offer a unique laboratory to break parameter degeneracies in chemical evolution models. This allows us to identify the effects of the main parameters guiding NSD nucleosynthesis and disentangle them from the global enrichment history. We also show for two edge cases how the mode of gas accretion onto the NSD imprints on the gas abundance profiles and make predictions that can be tested with observations.