Galaxies of the z ∼ 2 Universe. I. Grism-selected Rest-frame Optical Emission-line Galaxies

Euclid, the Wide Field Infrared Survey Telescope, and the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) will make emission-line selected galaxies the largest observed constituent in the z > 1 universe. However, we only have a limited understanding of the physical properties of galaxies selected via their Lyα or rest-frame optical emission lines. To address this problem, we present the basic properties of ∼2000 All-Wavelength Extended Groth Strip International Survey, Cosmological Evolution Survey, Great Observatories Origins Deep Survey-North, Great Observatories Origins Deep Survey-South, and Ultra Deep Survey galaxies identified in the redshift range 1.90 < z < 2.35 via their [O ii], Hβ, and [O iii] emission lines in the 3D-Hubble Space Telescope survey. For these z ∼ 2 galaxies, [O iii] is generally much brighter than [O ii] and Hβ, with typical rest-frame equivalent widths of several hundred Angstroms. Moreover, these strong emission-line systems span an extremely wide range of stellar mass (∼3 dex), star formation rate (∼2 dex), and [O iii] luminosity (∼2 dex). Comparing the distributions of these properties to those of continuum-selected galaxies, we find that emission-line galaxies have systematically lower stellar masses and lower optical/UV dust attenuations. These measurements lay the groundwork for an extensive comparison between these rest-frame optical emission-line galaxies and Lyα emitters identified in the HETDEX survey.