Ultra-Diffuse Galaxies in the Perseus Cluster: Comparing Galaxy Properties with Globular Cluster System Richness

TL;DR

This study investigates the structural and dynamical properties of five ultra-diffuse galaxies in the Perseus cluster, revealing differences in globular cluster richness and associated dark matter halo masses, with implications for galaxy evolution.

Contribution

It provides new spectroscopic measurements of UDGs' velocities and masses, linking globular cluster richness to dark matter content and galaxy dynamics in the Perseus cluster.

Findings

GC-rich UDGs have higher velocity dispersions than GC-poor UDGs.

No correlation found between GC numbers and cluster phase space positioning.

GC-rich UDGs possess greater dynamical mass within their half-light radius.

Abstract

It is clear that within the class of ultra-diffuse galaxies (UDGs) there is an extreme range in the richness of their associated globular cluster (GC) systems. Here, we report the structural properties of five UDGs in the Perseus cluster based on deep Subaru / Hyper Suprime-Cam imaging. Three appear GC-poor and two appear GC-rich. One of our sample, PUDG\_R24, appears to be undergoing quenching and is expected to fade into the UDG regime within the next $\sim0.5$ Gyr. We target this sample with Keck Cosmic Web Imager (KCWI) spectroscopy to investigate differences in their dark matter halos, as expected from their differing GC content. Our spectroscopy measures both recessional velocities, confirming Perseus cluster membership, and stellar velocity dispersions, to measure dynamical masses within their half-light radius. We supplement our data with that from the literature to examine trends in galaxy parameters with GC system richness. We do not find the correlation between GC numbers and UDG phase space positioning expected if GC-rich UDGs environmentally quench at high redshift. We do find GC-rich UDGs to have higher velocity dispersions than GC-poor UDGs on average, resulting in greater dynamical mass within the half-light radius. This agrees with the first order expectation that GC-rich UDGs have higher halo masses than GC-poor UDGs.