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Physics and Astronomy

Physics & Astronomy Colloquium

3:30 PM, Monday, November 10, 2014
Room 155, Chem-Phys Building

Dr. Elizabeth McGrath
Colby College


The Life and Death of Massive Galaxies

The average rate at which galaxies are forming stars in the Universe has decreased by more than an order of magnitude over the last 10 billion years. Understanding why certain galaxies shut off their star formation activity, while others do not is one of the key unanswered questions in astrophysics today. Observations in the local Universe suggest that the mechanism responsible for quenching star formation in galaxies may be intimately linked to both their mass assembly and their structural transformation from disks to spheroids. In order to test quenching scenarios, however, it is vital to look beyond the local Universe and identify the first generation of quiescent, "red and dead" galaxies at high redshift. I will discuss my work studying the rest-frame visible morphologies of the first massive systems to appear on the quiescent "red sequence" at redshifts z>1, when the universe was less than half its current age. Interestingly, a significant fraction (~30%) have morphologies dominated by massive exponential disks. The persistence of massive disks, long after star formation has ceased, implies that in at least some cases quenching precedes morphological transformation. I will examine what constraints these observations place on the mechanisms responsible for quenching the first generation of passive galaxies at z~2 and discuss them in context with an emerging picture of massive galaxy formation and evolution.

Refreshments will be served in CP 179 at 3:15 PM