Galaxy luminosity functions at redshifts 0.6–1.2 in the Chandra Deep Field South

Abstract

ABSTRACT We present the rest-frame ultraviolet (UV) galaxy luminosity function (LF) and luminosity density (LD) measurements in the far-UV (1500 Å) wavelength, in the redshift range $z$ = 0.6–1.2. The UV LF is derived using XMM-Newton Optical Monitor (XMM-OM), UV (1600–4000 Å) observations of the Chandra Deep Field South, over an area of 396 arcmin2. Using the deep UV imaging of the CDFS, we identified >2500 galaxies in our sample with UVW1AB ≤ 24.5 mag. This sample, along with various other catalogues containing redshift information, is used to calculate the binned representation of the galaxy UV LF in the two redshift bins 0.6 ≤ $z$ < 0.8 and 0.8 ≤ $z$ < 1.2, having a wide range of 1500 Å rest-frame UV magnitudes (ΔM1500 ≃ 3), reaching ≃ 1–1.5 magnitudes fainter than previous studies at similar redshifts. The binned LF is described well by the Schechter function form. Using maximum-likelihood, the Schechter function is fitted to the unbinned data to obtain the best-fitting values of the the UV galaxy LF parameters. We find that characteristic magnitude M* brightens by 0.8 mag from $z$ = 0.7 to $z$ = 1, implying an increase in the star formation activity between these redshifts, as reported by past studies. Our estimate of the faint-end slope $-1.10^{+0.19}_{-0.18}$ is on the shallower side compared with previous studies at $z$ = 0.7, whereas a value of $-1.56^{+0.19}_{-0.18}$ estimated for $z$ = 1.0, agrees with previous results given the uncertainties.