A Comprehensive Study of Hα Emitters at z ∼ 0.62 in the DAWN Survey: The Need for Deep and Wide Regions

Abstract

Abstract We present new estimates of the luminosity function (LF) and star formation rate density (SFRD) for an Hα-selected sample at z ∼ 0.62 from the Deep And Wide Narrow-band (DAWN) survey. Our results are based on a new Hα sample in the extended COSMOS region (compared to Coughlin et al.) with the inclusion of flanking fields, resulting in a total area coverage of ∼1.5 deg2. A total of 241 Hα emitters were selected based on robust selection criteria using spectrophotometric redshifts and broadband color–color classification. Given that dust extinction is a dominant uncertainty in the estimation of LF and SFRD, we explore the effect of different dust-correction prescriptions by calculating the LF and SFRD using a constant dust extinction correction, AHα = 1 mag, a luminosity-dependent correction, and a stellar-mass-dependent correction. The resulting Hα LFs are well fitted using Schechter functions with best-fit parameters: L* = 1042.24 erg s−1, ϕ* = 10−2.85 Mpc−3, α = −1.62 for constant dust correction, L erg s−1, ϕ* = 10−2.8 Mpc−3, α = −1.39 for luminosity-dependent dust correction, and L* = 1042.36 erg s−1, ϕ* = 10−2.91 Mpc−3, α = −1.48, for stellar-mass-dependent dust correction. The deep and wide nature of the DAWN survey effectively samples Hα emitters over a wide range of luminosities, thereby providing better constraints on both the faint and bright ends of the LF. Also, the SFRD estimates ρ SFR = 10−1.39 M ⊙ yr−1 Mpc−3 (constant dust correction), ρ SFR = 10−1.47 M ⊙ yr−1 Mpc−3 (luminosity-dependent dust correction), and ρ SFR = 10−1.46 M ⊙ yr−1 Mpc−3 (stellar-mass-dependent dust correction) are in good agreement with the evolution of SFRD across redshifts (0 < z < 2) seen from previous Hα surveys.