Sandro Tacchella, Michele Trenti, C. Marcella Carollo
We present a basic model to understand the redshift evolution of the UV luminosity and stellar mass functions of Lyman Break Galaxies. Our minimal approach is based on the assumption that the luminosity and stellar mass of a galaxy is related to its dark matter halo assembly and gas infall rate. Specifically, galaxies experience a burst of star formation at the halo assembly time, followed by a constant star formation rate, representing a secular star formation activity sustained by steady gas accretion. The model is calibrated by constructing a galaxy luminosity versus halo mass relation at z=4 via abundance matching. After this luminosity calibration, our model naturally fits the z=4 stellar mass function. Furthermore, it correctly predicts the evolution of both luminosity and stellar mass functions over 13 billion years, from z=0 to z=8. Star formation from steady gas accretion is the dominant contribution to the galaxy luminosity at all redshifts, but the initial burst of star formation contributes significantly to the stellar mass assembly and evolution of the stellar mass function. While the details of star formation efficiency and feedback are hidden within our calibrated luminosity versus halo mass relation, our study highlights that the primary driver of galaxy evolution across cosmic time is the build-up of dark matter halos, without the need to invoke a redshift dependent efficiency in converting gas into stars.
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http://arxiv.org/abs/1211.2825
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