Abstract:

In this Dissertation, I present my work on a variety of topics on galaxy evolution from the deep fields observed by the Hubble Space Telescope. I derive spectrophotometric redshifts for the 1308 galaxies from the GRism ACS Program for Extragalactic Science in the Hubble Ultra Deep Field (HUDF). For the 81 galaxies with spectroscopic redshifts between 0.5 and 1.5, the standard deviation in the fractional error in (1 + z ) is 0.046. Using this redshift catalog, I conduct two extragalactic studies:

(1) The B-band galaxy luminosity function at redshift one. This spectrophotometric redshift catalog is 95% complete at 27.2 AB mag, which is nearly two magnitudes deeper than previous studies. Therefore, I am able to accurately determine that the faint-end slope of the galaxy luminosity function (LF) is -1.32. By comparing to numerous published measurements at various redshifts, I find evidence for a steepening of the faint-end slope with redshift.

(2) The galaxy major merger fraction and merger number density between redshifts 0.5 and 2.5. After correcting for mass incompleteness, I find that the major merger fraction of massive galaxies is not proportional to a power-law in (1 + z ) at high redshift, but rather appears to peak at an approximate redshift of 1.3. From this merger fraction, I infer that roughly 42% of massive galaxies have undergone a major merger since redshift one. To extend these measurements to higher redshifts, I determine the merger history of Lyman break galaxies selected as BVi'-band dropouts from the Great Observatories Origins Deep Survey and the HUDF. I correct these high redshift merger statistics for contamination of low redshift early-type galaxies and low mass Galactic dwarfs. By adopting the published merger counts at low redshift, I find that the major merger number density for galaxies more luminous than -20.5 mag can be suitably fit by a two-component power-law, and peaks at an approximate redshift of 1.04. This evolution is qualitatively similar to that of X-ray selected AGN and provides circumstantial evidence that luminous AGN may be triggered by major mergers.