Dark matter content and dynamical masses of ultra-diffuse galaxies in the Coma cluster

TL;DR

This study investigates the dark matter content and dynamical masses of ultra-diffuse galaxies in the Coma cluster, focusing on their evolution from low-mass, young stellar systems to UDGs over billions of years.

Contribution

It provides new measurements of dark matter and dynamical masses for both present and future UDGs using deep observations and assesses their evolutionary pathways.

Findings

Total dynamical masses range from 5.5×10^9 to 1.4×10^11 solar masses.

Dark matter content within half-light radius varies among UDGs.

Methodology for studying present and future UDGs is discussed.

Abstract

Ultra-diffuse galaxies (UDGs) are spatially extended, low surface brightness stellar systems with regular elliptical-like morphology found in large numbers in galaxy clusters and groups. Studies of the internal dynamics and dark matter content of UDGs have been hampered by their low surface brightnesses. We identified a sample of low-mass early-type post-starburst galaxies, `future UDGs' in the Coma cluster still populated with young stars, which will passively evolve into UDGs in the next 5$-$10 Gyr. We collected deep observations for a sample of low-mass early-type galaxies in the Coma cluster using MMT Binospec, which includes present-day and future UDGs. We derived their dark matter content within a half-light radius (70$-$95%) and total dynamical masses ($M_{200}=5.5\cdot10^9-1.4\cdot10^{11} M_{\odot}$) assuming the Burkert density profile and assess how different proposed evolutionary channels affect dark and visible matter in UDGs. We also discuss observational methodology of present and future UDG studies.