A large, deep 3 deg${}^2$ survey of H$\hat{I}\pm$, [OIII], and [OII] emitters from LAGER: constraining luminosity functions

Abstract

We present our measurements of the H$\hat{I}\pm$, [OIII], and [OII] luminosity functions as part of the Lyman Alpha Galaxies at Epoch of Reionization (LAGER) survey using our samples of 1577 $z=0.47$ H$\hat{I}\pm$-, 3933 $z=0.93$ [OIII]-, and 5367 $z=1.59$ [OII]-selected emission line galaxies in a single 3 deg${}^2$ CTIO/Blanco DECam pointing of the COSMOS field. Our observations reach 5$\ddot{I}ƒ$ depths of $8.2\times 10^{-18}$ erg s${}^{-1}$ cm${}^{-2}$ and comoving volumes of $(1-7)\times 10^5$ Mpc${}^3$ making our survey one of the deepest narrowband surveys. We measure the observed luminosity functions and find best-fits of $\ddot{I}{•}^{\star }=10^{-3.16\pm 0.09}$ Mpc${}^{-3}$ and $L^{\star }=10^{41.72\pm 0.09}$ erg s${}^{-1}$ for H$\hat{I}\pm$, $\ddot{I}{•}^{\star }=10^{-2.16_{-0.12}^{+0.10}}$ Mpc${}^{-3}$ and $L^{\star }=10^{41.38_{-0.06}^{+0.07}}$ erg s${}^{-1}$ for [OIII], and $\ddot{I}{•}^{\star }=10^{-1.97_{-0.07}^{+0.07}}$ Mpc${}^{-3}$ and $L^{\star }=10^{41.66\pm 0.03}$ erg s${}^{-1}$ for [OII], with $\hat{I}\pm$ fixed to $-1.75$, $-1.6$, and $-1.3$, respectively. An excess of bright $>10^{42}$ erg s${}^{-1}$ [OIII] emitters is observed and may be due to AGN contamination. Dust corrections are applied assuming $A_{\mathrm{H}\hat{\mathrm{I}}\pm }=1$ mag. We also design our own empirical rest-frame $g-r$ calibration using SDSS DR12 data, test it against our $z=0.47$ H$\hat{I}\pm$ emitters with $z$COSMOS $1$D spectra, and calibrate it for $(g-r)$ between $-0.8$ and $1.3$ mag. Dust and AGN-corrected star formation rate densities (SFRDs) are measured as ${\log }_{10}\ddot{I}{}_{\mathrm{SFR}}/({\mathrm{M}}_{\odot }{\mathrm{yr}}^{-1}{\mathrm{Mpc}}^{-3})=-1.63\pm 0.04$, $-1.07\pm 0.06$, and $-0.90\pm 0.10$ for H$\hat{I}\pm$, [OIII], and [OII], respectively. We find our [OIII] and [OII] samples fully trace cosmic star formation activity at their respective redshifts in comparison to multi-wavelength SFRDs, while the H$\hat{I}\pm$ sample traces $\sim 70$ percent of the total $z=0.47$ SFRD.

21 pages, 12 figures, 6 Tables. Accepted by MNRAS for publication on 6 Jan 2020