Daniel Perley (CIT) -- Cosmic History and Galaxy Evolution as Seen by Gamma-Ray Bursts

Long-duration GRBs - the relativistic explosions of rare, massive stars - are the most luminous objects in the universe: GRBs have been observed out to z=8-9 and should be detectable in principle out to z~20. Thanks to their close connection with massive star formation, GRBs also provide a unique window into the star-formation history of the Universe and the evolution of galaxies. I will summarize some recent developments in the study of the GRB host population in the distant universe using data from a large observational campaign at Spitzer, Keck, VLT, VLA and other major facilities - providing new costraints on what factors appear to govern the GRB rate and on the properties and evolution of galaxies in the early universe. While GRBs are almost completely absent in moderate- to high-mass galaxies at z<1 (most likely because they are suppressed in high-metallicity environments), the mass distribution of the population shifts dramatically between 1<z<2 and the GRB and galaxy luminosity functions are in agreement at higher redshifts, revealing cosmological evolution in the properties of massive galaxies and (partially) alleviating some concerns about their ability to trace star-formation accurately at higher redshifts. I will also present new constraints on the distibution of dust in and among galaxies, the nature of the dust attenuation curve in starbursting high-z galaxies, the relative importance of ULIRGs and SMGs to cosmic star-formation out to z~2, and the fraction of star-formation captured by deep Spitzer surveys out to z~5.