"On the Formation of Massive Galaxies"
Looking backwards, using fossil evidence from nearby galaxies provides a plausible picture of how galaxies have formed over cosmic time. Also, going forwards, the present quite definite cosmological model, shows how perturbations grew from low amplitude fluctuations via standard physical processes to the present world. Finally, we can employ large telescopes as a time-machines – directly observing the past history of our light-cone. While none of these approaches gives results accurate to more than 5-10%, a plausible picture emerges. Massive galaxies form in two phases. In the first phase (~ redshift 6 to 2), cold gas streams in, making stars in a small (<1kpc) region, but as the stellar mass approaches 1011 Msolar, a hot bubble forms suppressing further inflow of cold gas. Then smaller stellar satellite systems are accreted; the size of the system grows by about a factor of three and the mass doubles. Energy release from gravitational infall terminates star-formation even in the absence of feedback. This physical picture seems naturally to lead to the mass, size, scale and epoch of galaxy formation and to a first understanding of the detailed internal structure of these systems.
The Princeton Plasma Physics Laboratory 2012-2013 Colloquium Committee is comprised of the following people. Please feel free to contact them by e-mail regarding any possible speakers or topics for future colloquia.