2020ApJ...892...30H

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, A_Hα = 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* = 10^42.24 erg s^–1, ph* = 10^–2.85 Mpc^–3, α = -1.62 for constant dust correction, L^* =10^42.31 erg s^–1, ph* = 10^–2.8 Mpc^–3, α = -1.39 for luminosity-dependent dust correction, and L* = 10^42.36 erg s^–1, ph* = 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.