A large, deep 3 deg2 survey of Hα, [OIII], and [OII] emitters from LAGER: constraining luminosity functions

We present our recent measurements of the Hα, [OIII], and [OII] luminosity functions as part of the Lyman Alpha Galaxies at Epoch of Reionization (LAGER) survey using our samples of ~11000 Hα, [OIII], and [OII] emitters at z = 0.47, 0.93, and 1.59, respectively, in a 3 deg² single, CTIO/Blanco DECam pointing of the COSMOS field. Our observations reach 5σ depths of 8.2x10^-18 erg s^-1 cm^-2 and comoving volumes of (1 - 7) x 10⁵ Mpc³ making our survey one of the deepest narrowband surveys. We will present how we select our emission line galaxy candidates and our method in measuring the luminosity functions. We will then discuss our luminosity functions in comparison to previous narrowband surveys. We find an excess of bright >10⁴² erg s^-1 [OIII] emitters (L > 3L^*) and discuss how this may be due to AGN contamination and its implications for the next-generation emission line surveys, such as the WFIRST High-Latitude Spectroscopic Survey (HLSS), which will primarily observe the bright-end of the luminosity function. We will discuss the various methods we used to correct for dust attenuation, including a new empirical calibration we have designed using SDSS rest-frame (g - r ) color and tested against z = 0.47 Hα emitters with zCOSMOS 1D spectra. We will present measurements of the star formation rate densities, where we find our [OIII] and [OII] samples trace the bulk of cosmic star formation activity at their respective redshifts, while our Hα sample traces about 70% of the total z = 0.47 star formation activity. We finally will present the equivalent width (EW) distributions of our samples and our method in parameterizing the distributions, taking into account selection effects and incompleteness. Our method has implications for future surveys, such as WFIRST HLSS, that are limited both in line flux and EW. Overall, our results are for one LAGER field, while the full survey will comprise 8 fields corresponding to 24 deg². We expect the full LAGER sample to have about 13000 Hα, 29000 [OIII], and 53000 [OII] emitters providing us with a large sample of narrowband-selected galaxies at their respective redshifts.