AstroSat detection of Lyman continuum emission from a z=1.42 galaxy
Direct detection of sources responsible for reionization of the universe from z>6 is practically infeasible due to the steep decline of IGM transmission. However, to understand the physical properties of such objects, one can study their analogues at low redshift universe where IGM is relatively transparent to ionizing or Lyman continuum photons. AstroSat/UVIT detect one such galaxies at z=1.42 based on the AUDF observations. This marks a direct detection in the middle of a redshift range where no detection of ionizing photons has been made before. This was the first time ionizing photons at rest-frame 600 Angstrom was detected from a distant star-forming galaxy. The aricle was published in Nature Astronomy in 2020.
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.