Star clusters as tools to study the formation and evolution of galaxies

• Grant number: 23/09086-7
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: August 01, 2023
• End date: July 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics
• Principal Investigator: Beatriz Leonor Silveira Barbuy
• Grantee: Emilio José Bento Zanatta
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 20/15245-2 - The multi-object spectrograph (MOSAIC) for the extremely large telescope: spectroscopy of stellar populations in the milky way and external galaxies, AP.ESP

Abstract

In order to help with the investigation of two of the most significant outstanding questions in current astrophysics, this initiative concentrates on the study of extragalactic star clusters. First, the shortcomings of the present generation of star population models in the promising near-infrared (NIR) wavelength region, as well as their inability to accurately mimic observed properties of extragalactic globular clusters (GCs). And secondly, the continuous discussion regarding the impact of large-scale environmental factors on the formation and growth of GCs and nuclear star clusters (NSCs). As such, this project is divided in two parts.The first part aims to construct semi-empirical models of single stellar populations (SSPs) using the X-Shooter Spectral Library (XSL), a state-of-the-art stellar library with unprecedented wavelength and spatial coverage. These models will incorporate varying abundance ratios in order to reproduce the observed spectra and photometry of extragalactic GCs. To this goal, this project will utilise the SynSSP package to compute synthetic SSP spectra based on the XSL. The observed integrated NIR spectra of GCs in the galaxy NGC 5128 (Centaurus A) and the photometric data of GCs around galaxies in the Virgo and Hydra clusters will be used to validate the models.The second part of the project focuses on investigating the specific frequency of low-mass galaxies in the Shapley Supercluster, particularly the galaxy cluster Abell 3558 at the very centre of Shapley. The purpose of the study is to examine the relationship between the nucleation fraction of galaxies and GC abundance. The study is an expansion of earlier work on galaxy nucleation in various environments, where strong evidence was found for the role of the large-scale environment in the formation and evolution of star clusters. The analysis will involve detecting GCs around dwarf galaxies in Abell 3558 using deep Hubble Space Telescope images. The number of GCs associated with each galaxy will be determined, and the GC specific frequencies will be examined to understand the relationship between GC distribution and nucleation. The findings will contribute to the understanding of star cluster formation and growth in extreme environments.Overall, the project aims to develop semi-empirical models to study extragalactic GCs and investigate the relationship between galaxy nucleation and GC abundance in the Shapley Supercluster.