Alma maging of the co (7−6) line emission in the submillimeter galaxy less 073 at z = 4.755

Journal article

In this paper we present our imaging observations on the CO (7−6) line and its underlying continuum emission of the young submillimeter galaxy LESS 073 at redshift 4.755, using the Atacama Large Millimeter/submillimeter Array (ALMA). At the achieved resolution of ∼1 ′′ .2 × 0 ′′ .9 (8 × 6 kpc2 ), the CO (7−6) emission is largely unresolved (with a deconvolved size of 1′′ .1(±0 ′′ .5) × 0 ′′ .9(±0 ′′ .8).), and the continuum emission is totally unresolved. The CO (7−6) line emission has an integrated flux of 0.86 ± 0.08 Jy km s−1 , and a line width of 343 ± 40 km s−1 . The continuum emission has a flux density of 0.51 mJy. By fitting the observed far-infrared (FIR) spectral energy distribution of LESS 073 with a single-temperature modified blackbody function, we obtained a dust temperature Tdust = 57.6 ± 3.5 K, 60-to-100 µm flux density ratio f60/f100 = 0.86 ± 0.08, and total infrared luminosity LIR = (5.8±0.9)×1012 L⊙. The SED-fit-based f60/f100 is consistent with those estimated from various line ratios as advocated by our earlier work, indicating that those proposed line-ratiobased method can be used to practically derive f60/f100 for high-z sources. The total molecular gas mass of LESS 073 is (3.3 ± 1.7) × 1010 M⊙, and the inferred gas depletion time is about 43 Myr.

Authors: Zhao, Y; Lu, N; Diaz-Santos, T; Gao, Y; Xu, K

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: Astrophysical Journal
• Volume: 892
• Issue: 2
• Article number: 145
• Publication date: 2020-04-07
• Acceptance date: 2020-02-11
• DOI: 10.3847/1538-4357/ab75eb
• EISSN: 1538-4357
• ISSN: 0004-637X
• Language: English
• Keywords: submillimeter: galaxies; galaxies: ISM; galaxies: active; galaxies: evolution; galaxies: nuclei; galaxies: starburst; FFR