Exploring the optical and infrared evolution of galaxies.

摘要

We track the evolution of galaxy optical and mid-infrared luminosity and color, morphology, and half-light radius, observables that are tied to their star formation history. In agreement with previous studies, we find that the B-band optical and total infrared luminosities of blue galaxies have declined since z = 1. We also find that the infrared luminosity of spiral galaxies has declined more rapidly than for peculiar/merger types. In addition, we find that the optical evolution can be explained by a radius dependent luminosity evolution. Assuming a linear shift in MB with z, we use a maximum likelihood method to quantify the evolution. Under these assumptions, large (R1/2 > 5 kpc), and intermediate sized (3 R1/2 5 kpc) galaxies, have experienced 1.55(+0.10, -0.15) and 1.70(+0.13, -0.10) magnitudes of dimming since z = 1. This luminosity evolution can be explained by a simple exponential decline in star formation with an e-folding tune of ∼ 3 Gyr. Meanwhile, small galaxies, or some subset thereof, have experienced more evolution, 2.40(+/-0.23) magnitudes. This factor of ten decline in luminosity is too large to be explained by simple exponential models, but can be explained by starbursting dwarf systems that fade rapidly, coupled with a decline in burst strength or frequency.; This thesis also prepares us for a detailed study of the sites and triggers of star formation in these galaxies. The Center for Adaptive Optics Treasury Survey has been observing the deep HST galaxies fields with high resolution near-infrared imaging with Keck adaptive optics (AO). In this thesis, we demonstrate that the combination of HST optical and near-IR from Keck AO allows us to measure the stellar population of galaxy substructures and to break the dust-age degeneracy. We also demonstrate that 10% photometry on faint extra-galactic systems is possible with Keck AO despite a point-spread-function that is varying both temporally and spatially. With the AO tools developed in this thesis and with an new understanding of the evolution of galaxy properties---size, luminosity, and color---we are now in a position to identify the triggers of star formation in distant galaxies.