Ultra-diffuse Galaxy Analogues in the Subaru Hyper-Suprime Cam Wide-field Clusters

Abstract

We perform a systematic statistical study of ultra-diffuse galaxy analogues (NUDGEs) in a large sample of galaxy clusters to investigate their properties with respect to the host clusters. We used data from the Hyper Suprime-Cam Subaru Strategic Program wide field survey and find a total of 5057 NUDGEs exceeding the background counts in 51 out of 66 galaxy clusters. The clusters span the redshift range 0.08$\,<\,$z$\,<\,$0.15 and they have a mass range of $0.95\times10^{14}\,\text{M}_\odot - 8.34\times10^{14}\,\text{M}_\odot$. The properties of these NUDGEs are found to be similar to UDGs studied in previous works and reaffirm that they are an extension of a continuous galaxy distribution. The number of NUDGEs as a function of cluster halo mass for our sample follows the power law: $N\propto M_{200}^{0.78\pm\,0.28} $. This fit is consistent with previous UDG studies and, together with our NUDGE sizes distributions, matches well with the simulations of UDGs in cored dark matter haloes formed by tidal stripping. The NUDGE density distribution with respect to clustercentric radius of our sample is flatter than previous UDG studies, although the red NUDGEs in this sample show a statistically significant decrease in density with respect to clustercentric radius, indicating that red UDGs may be more affected by their environment than blue UDGs.