Pure Exponential disks at redshift z~1
Pure disk galaxies without any bulge component, i.e., bulges that are neither classical nor pseudo, seem to have escaped the effects of merger activity that are inherent to hierarchical galaxy formation models as well as strong internal secular evolution. We discover that a significant fraction (15%-18%) of disk galaxies in the Hubble Deep Field (0.4 < z < 1.0) and in the local universe (0.02 < z <0.05) are such pure disk systems. It remains puzzling how such galaxies escaped the influence of inevitable mergers and interaction; even secular evolution effects. For details see: by Sachdeva and Saha (2016), published in ApJ Letters.