Properties of galaxies at the faint end of the H$\hat{I}\pm$ luminosity function at $z\sim 0.62$

Abstract

Studies measuring the star formation rate density, luminosity function, and properties of star-forming galaxies are numerous. However, it exists a gap at $0.5<z<0.8$ in H$\hat{I}\pm$-based studies. Our main goal is to study the properties of a sample of faint H$\hat{I}\pm$ emitters at $z\sim 0.62$. We focus on their contribution to the faint end of the luminosity function and derived star formation rate density, characterising their morphologies and basic photometric and spectroscopic properties. We use a narrow-band technique in the near-infrared, with a filter centred at 1.06 $\hat{I}¼$m. The data come from ultra-deep VLT/HAWK-I observations in the GOODS-S field with a total of 31.9 h in the narrow-band filter. We perform a visual classification of the sample and study their morphologies from structural parameters available in CANDELS. Our 28 H$\hat{I}\pm$-selected sample of faint star-forming galaxies reveals a robust faint-end slope of the luminosity function $\hat{I}\pm =-1.46_{-0.08}^{+0.16}$. The derived star formation rate density at $z\sim 0.62$ is $\ddot{I}{}_{\mathrm{SFR}}=0.036_{-0.008}^{+0.012}{M}_{\odot }\mathrm{y}{\mathrm{r}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-3}$. The sample is mainly composed of disks, but an important contribution of compact galaxies with Sérsic indexes $n\sim 2$ display the highest specific star formation rates. The luminosity function at $z\sim 0.62$ from our ultra-deep data points towards a steeper $\hat{I}\pm$ when an individual extinction correction for each object is applied. Compact galaxies are low-mass, low-luminosity, and starburst-dominated objects with a light profile in an intermediate stage from early to late types.

Published in Astronomy & Astrophysics. 19 pages, 14 figures. New version includes language edited by the journal