An ALMA Spectroscopic Survey of the Brightest Submillimeter Galaxies in the SCUBA-2-COSMOS Field (AS2COSPEC): Physical Properties of z=2-5 Ultra- and Hyperluminous Infrared Galaxies
The Astrophysical Journal(2023)
摘要
We report physical properties of the brightest (S_870 μ
m=12.4-19.2mJy) and not strongly lensed 18 870μm selected dusty
star-forming galaxies (DSFGs), also known as submillimeter galaxies (SMGs), in
the COSMOS field. This sample is part of an ALMA band3 spectroscopic survey
(AS2COSPEC), and spectroscopic redshifts are measured in 17 of them at
z=2-5. We perform spectral energy distribution analyses and deduce a median
total infrared luminosity of L_ IR=(1.3±0.1)×10^13 L_⊙,
infrared-based star-formation rate of SFR_
IR=1390±150 M_⊙ yr^-1, stellar mass of
M_∗=(1.4±0.6)×10^11 M_⊙, dust mass of M_
dust=(3.7±0.5)×10^9 M_⊙, and molecular gas mass of M_ gas=
(α_ CO/0.8)(1.2±0.1)×10^11 M_⊙, suggesting that they
are one of the most massive, ISM-enriched, and actively star-forming systems at
z=2-5. In addition, compared to less massive and less active galaxies at
similar epochs, SMGs have comparable gas fractions; however, they have much
shorter depletion time, possibly caused by more active dynamical interactions.
We determine a median dust emissivity index of β=2.1±0.1 for our
sample, and by combining our results with those from other DSFG samples, we
find no correlation of β with redshift or infrared luminosity, indicating
similar dust grain compositions across cosmic time for infrared luminous
galaxies. We also find that AS2COSPEC SMGs have one of the highest
dust-to-stellar mass ratios, with a median of 0.02±0.01, significantly
higher than model predictions, possibly due to too strong of a AGN feedback
implemented in the model. Finally, our complete and uniform survey enables us
to put constraints on the most massive end of the dust and molecular gas mass
functions.
更多查看译文
关键词
Galaxy evolution,Galaxy formation,Infrared galaxies,Interstellar line emission,Interstellar medium,Submillimeter astronomy
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要