Astronomy Colloquium: Michelle Collins

Date: Wed. September 2nd, 2015, 11:00 am-12:00 pm
Location: Sears 552

The faintest galaxies as probes of cosmology and galactic evolution

Michelle Collins (Yale)

As the faintest galaxies we are able to observe in the Universe, the dwarf spheroidals can be thought of as the fundamental galactic unit. Within our Local Group, we are able to study these objects in extremely high detail, resolving their mass profiles, chemistries, and evolutionary histories. These measurements have led to several surprising results. One is that the masses of these systems appear to be lower than predicted by cold dark matter simulations. Additionally, dwarf galaxies are not distributed isotropically around their hosts, as naively expected in the current cosmological paradigm. In this talk, I will discuss these observational peculiarities, and how we may account for them. I will then discuss a new class of ultra diffuse galaxy that was recently discovered in the distant Coma cluster. These wispy galaxies have luminosities similar to dwarf galaxies, but sizes similar to the Milky Way, which is 4 orders of magnitude brighter, intriguing astronomers. The key to understanding these unusual systems may lie in the detailed studies of nearby dwarf galaxies, whose properties are not so dissimilar to these more distant objects.