Doll Carriel, Goran (2025) Tracing the Origins of Ultra-Diffuse Galaxies: Insights from the LEWIS Project in the Hydra I Cluster. [Tesi di dottorato]

Documento PDF Goran_s_Thesis_revised_2.pdf Download (24MB)

Abstract

This thesis present the first systematic and comprehensive study on spectroscopic properties from UDGs and LSBs for Hydra-I. We leverage the LEWIS (Looking into the faintEst WIth MUSE) survey and MUSE IFU spectroscopy to analyze at least 10 galaxies of the original 25 (19 UDGs, 6 LSBs) within the inner 0.4Re of the cluster, deriving stellar kinematics, integrated stellar population properties (ages, metallicities, chemical abundances) and spatially resolved metallicity, [Mg/Fe] ratios and age gradients for four of such sources. Our integrated stellar population analysis reveals that most galaxies within the cluster follow the standard mass-metallicity relationship (MZR) for dwarf galaxies, with mean metallicities of <[M/H]> ≈ 0.9 ± 0.2 dex and intermediate-to-old ages (≈ 10 Gyr). However, we find a distinct sub-population of metal-rich outliers within the core of the cluster ("early infallers") that deviate from the standard MZR. Our two-dimensional analysis for a subset of the LEWIS sample reveals complex metallicity profiles, including flat, inverted and V-shaped. We also recover [α/Fe] gradients where we generally find strongly decreasing trends. We compare these results against simulations (TNG50, NIHAO) and conclude that the "failed scenario" cannot explain the observed properties within the HydraI cluster, as we find no evidence for extreme metal poor stars associated with massive halos. Instead, we find a complex scenario with evidence of many galaxies being "extended" or "puffed-up" dwarfs instead. High metallicity outliers coupled with non-standard metallicity profiles show further evidence of environmental processes contributing to the observed properties. These findings demonstrate that UDGs are not a monolithic class, but a diverse population whose extreme diffuseness arises from the coupling of internal baryonic physics with environmental history.

Downloads

Actions (login required)

Modifica documento