| 總結: | 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.
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