Dr. Benjamin D. Oppenheimer

Leiden University

"A Full-Scale Intervention of How Galaxies Form with New Constraints from the Circumgalactic Medium"

I will discuss using my cosmological hydrodynamic simulations to model a large variety of observations with specific emphasis on the diffuse gas residing in galactic halos, the circumgalactic medium (CGM). New observations by the Cosmic Origins Spectrograph on Hubble are making it possible to put key new constraints on the processes regulating galaxy formation, including the importance of feedback to enrich the CGM. I will also take a holistic view of metals in all phases: stars, ISM, the CGM, and the IGM to emphasize that superwind feedback is required across all epochs from z>6 until today. Critical to finding the diffuse metal budget are proper ionization correction of intergalactic metal absorption lines. I will share some new results regarding how AGNs turning on and off could keep metal ionization states out of equilibrium and change our interpretation of the amount of underlying metals traced around galaxies hosting episodic AGN. Finally, I will consider the 13 Gyr star formation histories of our simulated galaxies and compare to some new observational & theoretical constraints. New high-z constraints suggest that hydro simulations likely face significant challenges in building the right galaxies at the right time.

Back to Spring 2013 Astrophysics Seminars

Received Jan 10, 2013