Evolution of Galaxy Morphology

Abstract

A strictly empirical review is given of presently available data on the evolution of galaxy morphology. From HST observations of distant galaxies and ground-based observations of nearby ones observed at the same rest-frame wavelength it is found that late-type (Sbc-Sc) galaxies evolve more rapidly with increasing redshift than do early-type (E-Sa-Sab) galaxies. Furthermore the fraction of peculiar objects, that cannot be shoehorned into the Hubble tuning fork classification scheme, increases rapidly with redshift. Unexpectedly it is found that, over a wide range of densities, the fraction of barred galaxies is independent of environment. However, this fraction of barred galaxies appears to decline rapidly with increasing redshift.