2018MNRAS.481L..84M

Recent observations with the Atacama Large Millimeter/submillimeter Array (ALMA) detected far-infrared emission lines such as the [O III] 88µm line from galaxies at z ∼ 7-9. We use a cosmological simulation of galaxy formation to study the physical properties of [O III] 88µm emitters. In a comoving volume of 50 h^–1 Mpc on a side, we locate 34 galaxies with stellar masses greater than 10^{8^M}☉_ at z = 9, and more than 270 such galaxies at z = 7. We calculate the [O III] 88µm luminosities (L_ O III, 88_) by combining a physical model of H II regions with emission line calculations using the photoionization code CLOUDY. We show that the resulting L_ O III, 88_, for a given star formation rate, is slightly higher than predicted from the empirical relation for local galaxies, and is consistent with recent observations of galaxies at redshifts 7-9. Bright [O III] emitters with L_ O III, 88_> 10⁸^L_☉ have star formation rates higher than 3 M_☉ yr^–1, and the typical metallicity is ∼0.1 Z_☉. The galaxies are hosted by dark matter haloes with masses greater than 10¹¹ M_☉. We propose to use the [O III] 5007 Å line, to be detected by James Webb Space Telescope, to study the properties of galaxies whose [O III] 88µm line emission has been already detected with ALMA.