Dense and warm neutral gas in BR1202-0725 at z = 4.7 as traced by the [O I] 145 um line

Minju M. Lee; Tohru Nagao; Carlos De Breuck; Stefano Carniani; Giovanni Cresci; Bunyo Hatsukade; Ryohei Kawabe; Kotaro Kohno; Roberto Maiolino; Filippo Mannucci; Alessandro Marconi; Kouichiro Nakanishi; Paulina Troncoso; Hideki Umehata

doi:10.3847/1538-4357/abe7ea

arXiv · 2102.09219

Dense and warm neutral gas in BR1202-0725 at z = 4.7 as traced by the [O I] 145 um line

Minju M. Lee·Tohru Nagao·Carlos De Breuck·Stefano Carniani·Giovanni Cresci·Bunyo Hatsukade·Ryohei Kawabe·Kotaro Kohno·Roberto Maiolino·Filippo Mannucci·Alessandro Marconi·Kouichiro Nakanishi·Paulina Troncoso·Hideki Umehata

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Abstract

We report the detection of [O I]145.5um in the BR 1202-0725 system, a compact group at z=4.7 consisting of a quasar (QSO), a submillimeter-bright galaxy (SMG), and three faint Lya emitters. By taking into account the previous detections and upper limits, the [O I]/[C II] line ratios of the now five known high-z galaxies are higher than or on the high-end of the observed values in local galaxies ([O I]/[C II]$\gtrsim$0.13). The high [O I]/[C II] ratios and the joint analysis with the previous detection of [N II] lines for both the QSO and the SMG suggest the presence of warm and dense neutral gas in these highly star-forming galaxies. This is further supported by new CO (12-11) line detections and a comparison with cosmological simulations. There is a possible positive correlation between the [NII]122/205 line ratio and the [O I]/[C II] ratio when all local and high-z sources are taken into account, indicating that the denser the ionized gas, the denser and warmer the neutral gas (or vice versa). The detection of the [O I] line in the BR1202-0725 system with a relatively short amount of integration with ALMA demonstrates the great potential of this line as a dense gas tracer for high-z galaxies.

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Minju M. Lee, Tohru Nagao, Carlos De Breuck, Stefano Carniani, Giovanni Cresci, Bunyo Hatsukade, Ryohei Kawabe, Kotaro Kohno, Roberto Maiolino, Filippo Mannucci, Alessandro Marconi, Kouichiro Nakanishi, Paulina Troncoso, Hideki Umehata. 2021-02-18. Dense and warm neutral gas in BR1202-0725 at z = 4.7 as traced by the [O I] 145 um line. https://doi.org/10.3847/1538-4357%2Fabe7ea

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