Probing the nuclear star cluster of galaxies with ELTs

TL;DR

Next-generation ELTs will enable direct age estimation of nuclear star clusters in galaxies up to 5 Mpc away by resolving main-sequence turn-off stars, surpassing current integrated light methods.

Contribution

This study demonstrates the feasibility of using ELTs to analyze NSC stellar populations through resolved photometry, a significant advancement over unresolved integrated light analysis.

Findings

Main-sequence turn-off detectable up to 2 Mpc for old populations

Age estimation possible up to 3 Mpc for intermediate-age populations

Performance of TMT and E-ELT are comparable for this science case

Abstract

The unprecedented sensitivity and spatial resolution of next generation ground-based extremely large telescopes (ELTs) will open a completely new window on the study of resolved stellar populations. In this paper we study the feasibility of the analysis of nuclear star cluster (NSC) stellar populations with ELTs. To date, NSC stellar population studies are based on the properties of their integrated light. NSC are in fact observed as unresolved sources even with the HST. We explore the possibility to obtain direct estimates of the age of NSC stellar populations from photometry of main-sequence turn-off stars. We simulated ELT observations of NSCs at different distances and with different stellar populations. Photometric measurements on each simulated image were analysed in detail and results about photometric accuracy and completeness are reported here. We found that the main-sequence turn-off is detectable -and therefore the age of stellar populations can be directly estimated- up to 2Mpc for old, up to 3 Mpc for intermediate-age and up to 4-5 Mpc for young stellar populations. We found that for this particular science case the performances of TMT and E-ELT are of comparable quality.