| Galaxies are giant machines that turn gas into stars and the rate at which they were doing this was highest around redshift z=2, when the universe was only 1/4 of its present age. This is "cosmic high noon", and I will discuss both star-forming (live) and quiescent (dead) galaxies at z~2. My choice of this live/dead terminology here is not just a fanciful analogy but is central to my talk: I will show how the starforming-to-quiescent transition follows rules that are very similar to those that govern human death, leading not only to a well-justified "live/dead" terminology for star forming and quiescent galaxies, but to a simple and direct explanation for the Schechter-like stellar mass function for massive galaxies and potential insights into the quenching mechanism itself. |