2019/10/30 by Prole, Daniel J., van der Burg, Remco F. J., Hilker, Michael +1
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.1910.14057
While much of the focus around Ultra-Diffuse Galaxies (UDGs) has been given to those in galaxy groups and clusters, relatively little is known about them in less-dense environments. These isolated UDGs provide fundamental insights into UDG formation because environmentally driven evolution and survivability play less of a role in determining their physical and observable properties. We have recently conducted a statistical analysis of UDGs in the field using a new catalogue of sources detected in the deep Kilo-Degree Survey (KiDS) and Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) optical imaging surveys. Using an empirical model to assess our contamination from interloping sources, we show that a scenario in which cluster-like quiescent UDGs occupy a large fraction of the field UDG population is unlikely, with most being significantly bluer and some showing signs of localised star formation. We estimate an upper-limit on the total field abundance of UDGs of 8±3×10-3cMpc-3 within our selection range. The mass formation efficiency of UDGs implied by this upper-limit is similar to what is measured in groups and clusters, meaning that secular formation channels may significantly contribute to the overall UDG population.