Hα Emitting Galaxies at z ∼ 0.6 in the Deep And Wide Narrow-band Survey

Abstract

We present new measurements of the H α luminosity function (LF) and star formation rate (SFR) volume density for galaxies at z  ∼ 0.62 in the COSMOS field. Our results are part of the Deep And Wide Narrow-band Survey (DAWN), a unique infrared imaging program with large areal coverage (∼1.1 deg 2 over five fields) and sensitivity ( at 5 σ ). The present sample, based on a single DAWN field, contains 116 H α emission-line candidates at z  ∼ 0.62, 25% of which have spectroscopic confirmations. These candidates have been selected through the comparison of narrow and broad-band images in the infrared and through matching with existing catalogs in the COSMOS field. The dust-corrected LF is well described by a Schechter function with erg s −1 , Mpc −3 , erg s −1 Mpc −3 , and α  = −1.75 ± 0.09. From this LF, we calculate a SFR density of ρ SFR  = 10 −1.37 ± 0.08 M ⊙ yr −1 Mpc −3 . We expect an additional cosmic variance uncertainty of ∼20%. Both the faint end slope and luminosity density that we derive are consistent with prior results at similar redshifts, with reduced uncertainties. We also present an analysis of these H α emitters’ sizes, which shows a direct correlation between the galaxies’ sizes and their H α emission.