Friday, August 3, 2012

1208.0002 (G. Stinson et al.)

Making Galaxies in a Cosmological Context: The Need for Early Stellar Feedback    [PDF]

G. Stinson, C. Brook, A. V. Macciò, J. Wadsley, T. R. Quinn, H. M. P. Couchman
We introduce the Making Galaxies in a Cosmological Context (MaGICC) program of smoothed particle hydrodynamics (SPH) simulations. We describe a parameter study of galaxy formation simulations of an L* galaxy that uses early stellar feedback combined with supernova feedback to match the stellar mass--halo mass relationship. While supernova feedback alone can reduce star formation enough to match the stellar mass--halo mass relationship, the galaxy forms too many stars before z=2 to match the evolution seen using abundance matching. Our early stellar feedback is purely thermal and thus operates in a fundamentally different way than radiation pressure. The main effect of our implementation of early stellar feedback is to preheat the interstellar medium so that supernovae can drive outflows. The stronger feedback reduces the star formation efficiency beyond what supernovae alone can accomplish. As a result of the early stellar feedback, simulations produce a disk galaxy with a flat rotation curve, an exponential surface brightness profile that are also able to match a wide range of disk scaling relationships. The disk forms from the inside-out with an increasing exponential scale length as the galaxy evolves. Overall, early stellar feedback helps to simulate galaxies that match observational results at low and high redshifts.
View original: http://arxiv.org/abs/1208.0002

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