Measuring Stellar Masses of Emission Line Galaxies at 1.2<z<1.9

Abstract: The accurate measurement of stellar masses over a wide range of galaxy properties is essential for better constraining models of galaxy evolution. Emission line galaxies (ELGs) tend to have better redshift estimates than continuum-selected objects and have been shown to span a large range of physical properties, including stellar mass. Using data from the 3D-HST Treasury program, we construct a carefully vetted sample of 4350 ELGs at redshifts 1.16<z<1.90. We combine the 3D-HST emission line fluxes with far-UV through near-IR photometry and use the MCSED spectral energy distribution fitting code to constrain the galaxies' physical parameters, such as their star formation rate (SFRs) and stellar masses. Our sample is consistent with the z~2 mass-metallicity relation. More importantly, we show there is a simple but tight correlation between stellar mass and absolute magnitude in a near-IR filter that will be particularly useful in quickly calculating accurate stellar masses for millions of galaxies in upcoming missions such as Euclid and the Nancy Grace Roman Space Telescope.