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Evan Scannapieco (University of California, Berkeley)
Using semianalytic and numerical techniques, we show that the winds identified with high-redshift, low-mass galaxies may strongly affect the formation of stars in more massive galaxies that form later. With 3D realizations of a simple nonlinear growth model we track gas shocking, metal enrichment, cooling, and dark halo formation. Winds typically strip baryonic material out of pre-virialized intermediate mass halos, suppressing star formation. More massive halos trap the heated gas but collapse later, leading to a larger characteristic metallicity. This scenario accounts for the observed bell-shaped luminosity function of early-type galaxies, explains the small number of Milky-Way satellite galaxies relative to standard Cold Dark Matter prescriptions, and provides a reasonable explanation for the lack of metal-poor disk stars in the Milky Way and in other massive galaxies. We investigate ``Baryonic stripping'' in greater detail using a Smoothed Particle Hydrodynamic code to conduct two detailed simulations of a (5.2 Mpc/h)3 comoving volume of the Universe. In both simulations, we implement a simple model for star formation, while our second simulation also includes a ``blow-out'' model of galaxy outflows in which supernova driven winds from newly formed disk galaxies punch-out and shock the intergalactic medium while leaving the objects themselves intact. These simulations uncover a significant population of ~109 solar mass objects whose formation is suppressed by the mechanism of baryonic stripping, confirming the results of our semi-analytical investigation.
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The author(s) of this abstract have provided an email address for comments about the abstract: evan@orion.berkeley.edu