A dense, solar metallicity ISM in the z = 4.2 dusty star-forming galaxy SPT 0418-47

Carlos De Breuck, Axel Weiß, Matthieu Béthermin, Daniel Cunningham, Yordanka Apostolovski, Manuel Aravena, Melanie Archipley, Scott Chapman, Chian Chou Chen, Jianyang Fu, Sreevani Jarugula, Matt Malkan, Amelia C. Mangian, Kedar A. Phadke, Cassie A. Reuter, Gordon Stacey, Maria Strandet, Joaquin Vieira, Amit Vishwas

Research output: Contribution to journalArticlepeer-review


We present a study of six far-infrared fine structure lines in the z = 4.225 lensed dusty star-forming galaxy SPT 0418-47 to probe the physical conditions of its interstellar medium (ISM). In particular, we report Atacama Pathfinder EXperiment (APEX) detections of the [OI] 145 μm and [OIII] 88 μm lines and Atacama Compact Array (ACA) detections of the [NII] 122 and 205 μm lines. The [OI] 145 μm/[CII] 158 μm line ratio is ∼5× higher compared to the average of local galaxies. We interpret this as evidence that the ISM is dominated by photo-dissociation regions with high gas densities. The line ratios, and in particular those of [OIII] 88 μm and [NII] 122 μm imply that the ISM in SPT 0418-47 is already chemically enriched to nearly solar metallicity. While the strong gravitational amplification was required to detect these lines with APEX, larger samples can be observed with the Atacama Large Millimeter/submillimeter Array (ALMA), and should allow observers to determine if the dense, solar metallicity ISM is common among these highly star-forming galaxies.

Original languageEnglish (US)
Article numberA167
JournalAstronomy and Astrophysics
StatePublished - Nov 1 2019


  • Galaxies: ISM
  • Galaxies: high-redshift
  • Submillimeter: ISM
  • Submillimeter: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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