Edge-on galaxies in the HST COSMOS field: the evolution of stellar discs up to z ∼ 0.5

Abstract

ABSTRACT We present a sample of 950 edge-on spiral galaxies found with the use of an artificial neural network in the Hubble Space Telescope COSMOS field. This is currently the largest sample of distant edge-on galaxies. For all galaxies we analysed the 2D brightness distributions in the F814W filter and measured the radial and vertical exponential scales (h and hz correspondingly) of the brightness distribution. By comparing the characteristics of distant galaxies with those of nearby objects, we conclude that thin stellar discs with h/hz ≥ 10 at z ≈ 0.5 should be rarer than today. Both exponential scales of the stellar disc show evidence of luminosity-dependent evolution: in faint galaxies the h and hz values do not change with z, in bright (and massive) spiral galaxies both scales, on average, grow towards our epoch.