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

TL;DR

This study measures the UV galaxy luminosity function in the redshift range 0.6 to 1.2 using deep UV imaging from the Chandra Deep Field South, revealing evolution in galaxy brightness and star formation activity.

Contribution

It provides new measurements of the UV luminosity function at z=0.6-1.2, reaching fainter magnitudes than previous studies, and analyzes the evolution of galaxy brightness and star formation.

Findings

Characteristic magnitude brightens by 0.8 mag from z=0.7 to z=1.

Faint-end slope at z=0.7 is shallower than previous studies.

Faint-end slope at z=1.0 is consistent with previous results.

Abstract

We present the rest-frame Ultra-Violet (UV) galaxy luminosity function (LF) and luminosity density (LD) measurements in the far-UV (150 nm) wavelength, in the redshift range z = 0.6 - 1.2. The UV LF is derived using XMM-Newton Optical Monitor (XMM-OM), ultraviolet (160 - 400 nm) observations of the Chandra Deep Field South, over an area of 396 sq. arcmin. Using the deep UV imaging of the CDFS, we identified more than 2500 galaxies in our sample with faint UVW1(AB) limit 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 - 0.8 and 0.8 - 1.2, having a wide range of 150 nm rest-frame UV magnitudes, 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-fit values of the the UV galaxy LF parameters. We find that characteristic magnitude 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.