How is current galaxy structure related to very early galaxies and the history of galaxy formation?
How do galaxies form and grow? Do they form hierarchically through a process of agglomeration of similar units, or do they form through a large-scale gravitational instability? If the former is the case, the diversity in morphological types of galaxies, and their luminosities, mass, and size, would be a consequence of the stage in the agglomeration process a given galaxy stopped growing. If the latter is the case, this diversity must be a reflection of widely varied initial conditions at the onset of the gravitational instability. The answer to the question of galaxy formation requires measurement of the luminosity distribution and structure of galaxies, through cosmic time and back to the emergence of galaxy-size units in the early universe. Because of the need to look far back in time, and therefore to significant redshifts, the answer will be found in visible and near-to-mid infrared high sensitivity, high spatial resolution (D ~ 0.1″) observations.
