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

We present new measurements of the Hα 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 deg² over five fields) and sensitivity ( at 5σ). The present sample, based on a single DAWN field, contains 116 Hα 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 _o 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 Hα emitters' sizes, which shows a direct correlation between the galaxies' sizes and their Hα emission.