The H α and [O iii ] λ 5007 Luminosity Functions of 1.2 < z < 1.9 Emission-line Galaxies from Hubble Space Telescope (HST) Grism Spectroscopy.

Euclid and the Roman Space Telescope (Roman) will soon use grism spectroscopy to detect millions of galaxies via their H α and [O iii ] λ 5007 emission. To better constrain the expected galaxy counts from these instruments, we use a vetted sample of 4239 emission-line galaxies from the 3D Hubble Space Telescope survey to measure the H α and [O iii ] λ 5007 luminosity functions between 1.16 < z < 1.90; this sample is ∼4 times larger than previous studies at this redshift. We find very good agreement with previous measurements for H α, but for [O iii ], we predict a higher number of intermediate-luminosity galaxies than from previous works. We find that, for both lines, the characteristic luminosity,  * , increases monotonically with redshift, and use the H α luminosity function to calculate the epoch's cosmic star formation rate density. We find that H α -visible galaxies account for ∼81% of the epoch's total star formation rate, and this value changes very little over the 1.16 < z < 1.56 redshift range. Finally, we derive the surface density of galaxies as a function of limiting flux and find that previous predictions for galaxy counts for the Euclid Wide Survey are unchanged, but there may be more [O iii ] galaxies in the Roman High Latitude Survey than previously estimated. [ABSTRACT FROM AUTHOR]