Wagg, J.J.WaggAravena, M.M.AravenaBrisbin, D.D.BrisbinValtchanov, I.I.ValtchanovCarilli, C.C.CarilliDaddi, E.E.DaddiDannerbauer, H.H.DannerbauerDECARLI, ROBERTOROBERTODECARLIDíaz-Santos, T.T.Díaz-SantosRiechers, D.D.RiechersSargent, M.M.SargentWalter, F.F.Walter2021-12-102021-12-1020200035-8711http://hdl.handle.net/20.500.12386/31226We present Herschel-PACS spectroscopy of four main-sequence star-forming galaxies at z ∼ 1.5. We detect [OI]63-=μm line emission in BzK-21000 at z = 1.5213, and measure a line luminosity, $L_{\rm [O\, {\small I}]63\, \mu m} = (3.9\pm 0.7)\times 10^9$ -=L<SUB>⊙</SUB>. Our PDR modelling of the interstellar medium in BzK-21000 suggests a UV radiation field strength, G ∼ 320G<SUB>0</SUB>, and gas density, n ∼ 1800-=cm<SUP>-3</SUP>, consistent with previous LVG modelling of the molecular CO line excitation. The other three targets in our sample are individually undetected in these data, and we perform a spectral stacking analysis which yields a detection of their average emission and an [O-=I]63-=μm line luminosity, $L_{\rm [O\, {\small I}]63\, \mu m} = (1.1\pm 0.2)\times 10^9$ -=L<SUB>⊙</SUB>. We find that the implied luminosity ratio, $L_{\rm [O\, {\small I}]63\, \mu m}/L_{\rm IR}$ , of the undetected BzK-selected star-forming galaxies broadly agrees with that of low-redshift star-forming galaxies, while BzK-21000 has a similar ratio to that of a dusty star-forming galaxy at z ∼ 6. The high [O-=I]63-=μm line luminosities observed in BzK-21000 and the z ∼ 1-3 dusty and sub-mm luminous star-forming galaxies may be associated with extended reservoirs of low density, cool neutral gas.STAMPAenArticle10.1093/mnras/staa28842-s2.0-85096899279WOS:000587762900017https://academic.oup.com/mnras/article/499/2/1788/5909056http://arxiv.org/abs/2009.08984v12020MNRAS.499.1788WFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation