The Star Formation History of Rubin’s Galaxy

Rubin’s Galaxy (UGC 2885) is a fascinating example of galaxy evolution. It is a massive spiral, with a stellar mass roughly ten times that of the Milky Way, yet it has essentially no bulge. This gentle giant seems to be the product of passive IGM gas accretion instead of violent galaxy mergers. Very likely, Rubin’s Galaxy is an evolved low surface brightness spiral. Most low surface brightness spirals are much smaller, gas-rich galaxies that form stars slowly, and preferentially near the disk edges. Indeed, even with its impressive mass, UGC 2885 is an intermediate surface brightness galaxy. Here we present the spatially resolved star-formation history of UGC 2885, modeled using using ground-based IFU spectra in tandem with space-based UV and IR observations. These results allow us to look back through the history of Rubin’s Galaxy, and view its assembly history via the information fossilized in the stellar population.