HiZELS: a high-redshift survey of Hα emitters - II. The nature of star-forming galaxies at<i>z</i>= 0.84

Abstract

New results from a large survey of Hα emission-line galaxies at z = 0.84 using the Wide Field CAMera on UKIRT and a custom narrow-band filter in the J band are presented as part of the HiZELS survey. The deep narrow-band images reach an effective flux limit of FHα ∼ 10−16 erg s−1 cm−2 in a co-moving volume of 1.8×105 Mpc3, resulting in the largest and deepest survey of its kind ever done at z ∼ 1. There are 1517 potential line emitters detected across ∼ 1.4 square degrees (in two fields: COSMOS and UKIDSS UDS), of which 743 are selected as Hα emitters, based on their photometric and spectroscopic redshifts. These are then used to calculate the Hα luminosity function, which is well-fitted by a Schechter function with L ∗ = 1042.26±0.05 erg s−1, φ∗=10−1.92±0.10 Mpc−3 and α = −1.65 ± 0.15, and are used to estimate the volume average star formation rate at z = 0.845, ρSFR: 0.15 ± 0.01M yr−1 Mpc−3 (corrected for 15 % AGN contamination and integrated down to 2.5 Myr−1). These results robustly confirm a strong evolution of ρSFR from the present day out to z ∼ 1 and then flattening to z ∼ 2 using a single star-formation indicator: Hα luminosity. Out to z ∼ 1, both the characteristic luminosity and space density of the Hα emit-