The Formation of the Hubble Sequence

Abstract

Understanding when galaxies form via star formation histories and stellar mass assembly rates is becoming known with some certainty, yet the connection between high redshift and low redshift galaxy populations is not yet clear. By identifying and studying individual massive galaxies at high-redshifts, z > 1.5, we can uncover the physical effects that drove galaxy formation. Using the structures of high-z galaxies, as imaged with the Hubble Space Telescope, we argue that it is now possible to directly study the progenitors of ellipticals and disks. We also briefly describe early results that suggest many massive galaxies are forming at z>2 through major mergers.