The distribution and physical properties of high-redshift [O iii] emitters in a cosmological hydrodynamics simulation

Abstract

ABSTRACT Recent observations with the Atacama Large Millimeter/submillimeter Array (ALMA) detected far-infrared emission lines such as the [O iii] $88\,\mu \mathrm{ m}$ line from galaxies at z ∼ 7−9. We use a cosmological simulation of galaxy formation to study the physical properties of [O iii] $88\,\mu \mathrm{ m}$ emitters. In a comoving volume of 50 h−1 Mpc on a side, we locate 34 galaxies with stellar masses greater than $10^8\ \rm M_{\odot }$ at z = 9, and more than 270 such galaxies at z = 7. We calculate the [O iii] $88\,\mu \mathrm{ m}$ luminosities ($L_{{\rm O\,{{\rm {\small{III}}}, 88}}}$) by combining a physical model of H ii regions with emission line calculations using the photoionization code cloudy. We show that the resulting $L_{{\rm O\,{{\rm {\small{III}}}, 88}}}$, 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 $L_{{\rm O\,{{\rm {\small{III}}}, 88}}}\gt 10^8\, \rm L_{\odot }$ have star formation rates higher than $3\,\rm M_{\odot }\,{\rm yr}^{-1}$, and the typical metallicity is ${\sim } 0.1\, \rm Z_{\odot }$. The galaxies are hosted by dark matter haloes with masses greater than $10^{11}\, \rm M_{\odot }$. 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] $88\,\mu \mathrm{ m}$ line emission has been already detected with ALMA.