2016A&A...591A.151G

Context. 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 Hα-based studies.
Aims. Our main goal is to study the properties of a sample of faint Hα emitters at z∼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.
Methods. We use a narrow-band technique in the near-infrared, with a filter centred at 1.06µm. The data come from ultra-deep VLT/HAWK-I observations in the GOODS-S field with a total of 31.9h in the narrow-band filter. In addition to our survey, we mainly make use of ancillary data coming from the CANDELS and Rainbow Cosmological Surveys Database, from the 3D-HST for comparison, and also spectra from the literature. We perform a visual classification of the sample and study their morphologies from structural parameters available in CANDELS. In order to obtain the luminosity function, we apply a traditional V/V_max method and perform individual extinction corrections for each object to accurately trace the shape of the function.
Results. Our 28 Hα-selected sample of faint star-forming galaxies reveals a robust faint-end slope of the luminosity function α=-1.46_–0.08^+0.16. The derived star formation rate density at z∼0.62 is ρ_SFR=0.036_–0.008^+0.012M_☉/yr/Mpc³. The sample is mainly composed of disks, but an important contribution of compact galaxies with Sersic indexes n∼2 display the highest specific star formation rates.
Conclusions. The luminosity function at z∼0.62 from our ultra-deep data points towards a steeper α 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.