The properties of intensely star-forming galaxies 1 Gyr after the Big Bang

I discuss the properties of Lyman Break galaxies (LBGs) at z > 5 as determined from desperate fields covering approximately 500 arcmin2. I focus on the detailed physical properties of the sources in this large survey (~100 with spectroscopic redshifts). Specifically, I discuss ensemble mass estimates, stellar mass surface densities, core phase space densities, star-formation intensities, characteristics of their stellar populations, etc as obtained from multi-wavelength data (rest-frame UV through optical). I also discuss some caveats in the current interpretations often cited in the literature. The general picture that emerges from these studies is that these galaxies, observed about 1 Gyr after the Big Bang, have properties consistent with being the progenitors of the densest stellar systems in the local Universe — the centers of old bulges and early type galaxies.