What ultra-diffuse galaxies tell us about galaxy formation
Zili Shen
Graduate Student
Department of Astronomy
Yale University
The formation of ultra-diffuse galaxies (UDGs) is not well-understood. UDGs have large sizes (several kpc) for their dwarf-galaxy-like stellar mass, and have a wide range in dark matter content and other observed properties. In particular, NGC1052-DF2 and NGC1052-DF4 are two puzzling UDGs: they have low velocity dispersions indicating little to no dark matter content, as well as overly luminous and large globular clusters compared to the Milky Way population. Our group proposed a new model where these two galaxies formed jointly in the aftermath of a single bullet-cluster-like collision of dwarf galaxies. This is the first formation theory that can explain all the abnormal properties of both galaxies. In the NGC1052 group, we discovered a linear substructure of seven to eleven large, low-luminosity dwarf galaxies which include DF2 and DF4. I will discuss observational tests of the bullet dwarf model and future plans to expand our UDG sample size with the Dragonfly Ultrawide survey.
Hosted by Prof. Kirby