9/10/15: SO/NOAO Joint Colloquium Series: Dan McIntosh, Univ. of Missouri-Kansas City

Title: Galactic Capitalism: The Buildup of a Bimodal Galaxy Population

Our understanding of the universe is intimately tied to our study of galaxies.
These behemoths are the birth place of all stars, which in turn are the crucibles that created the chemistry of life. Physically, galaxies are dense condensations of normal baryonic matter at the centers of deep gravitational wells of dark matter that define the underlying backbone of the cosmos. As such, the formation of new suns turn galaxies into blazing beacons that allow us to map the universe in both time and space. Yet, star formation has been steadily waning since "Cosmic High Noon", an epoch 10 billion years ago when galactic activity was booming.

Conversely, individual galaxies continue to amass stars to the present day, and the number of spheroidal heavy weights is ballooning. In other words, a key feature of cosmic history is a 'galactic capitalism' of mergers and acquisitions that is producing a growing divide in the bimodal galaxy population of the `haves' and the `have nots'. The growth of galaxies and the simultaneous decline of star formation are understood broadly in the context of the standard cosmological model. Yet, an enduring mystery remains as to what exactly is killing off the production of new stars and what is reshaping disks into spheroidal galaxies at all cosmic epochs. I will discuss the latest theories of galaxy formation and growth, and focus on recent advances my team has been involved with that shed new light on the physical processes that quench star formation and reshape the structure of galaxy giants.