Emission-line-selected galaxies at z = 0.6–2 in GOODS South: Stellar masses, SFRs, and large-scale structure^⋆

¹ Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
e-mail: ia@dark-cosmology.dk
² Abastumani Astrophysical Observatory, Ilia State University, Kakutsa Cholokashvili Ave 3/5, 0162 Tbilisi, Georgia
³ European Southern Observatory, Karl Schwarzschild Strasse 2, 85748 Garching bei München, Germany
⁴ Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ, 85721, USA
⁵ CRAL, Observatoire de Lyon, Université Lyon 1, 9 avenue Ch. André, 69561 Saint Genis Laval Cedex, France
⁶ Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
⁷ INAF–Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy

Received: 17 December 2014
Accepted: 10 April 2015

Abstract

We have obtained deep NIR narrow and broad (J and Y) band imaging data of the GOODS-South field. The narrow band filter is centered at 1060 nm corresponding to redshifts z = 0.62,1.15,1.85 for the strong emission lines Hα, [Oiii]/Hβ and [Oii], respectively. From those data we extract a well defined sample (M(AB) = 24.8 in the narrow band) of objects with large emission line equivalent widths in the narrow band. Via SED fits to published broad band data we identify which of the three lines we have detected and assign redshifts accordingly. This results in a well defined, strong emission line selected sample of galaxies down to lower masses than can easily be obtained with only continuum flux limited selection techniques. We compare the (SED fitting-derived) main sequence of star-formation (MS) of our sample to previous works and find that it has a steeper slope than that of samples of more massive galaxies. We conclude that the MS steepens at lower (below M_⋆ = 10^9.4M_⊙) galaxy masses. We also show that the SFR at any redshift is higher in our sample. We attribute this to the targeted selection of galaxies with large emission line equivalent widths, and conclude that our sample forms the upper boundary of the MS. We briefly investigate and outline how samples with accurate redshifts down to those low stellar masses open a new window to study the formation of large scale structure in the early universe. In particular we report on the detection of a young galaxy cluster at z = 1.85 which features a central massive galaxy which is the candidate of an early stage cD galaxy, and we identify a likely filament mapped out by [Oiii] and Hβ emitting galaxies at z = 1.15.