分类： 天文学 >> 天文学 提交时间： 2023-02-19
G. J. Bendo
S. A. Urquhart
S. Serjeant
T. Bakx
M. Hagimoto
P. Cox
R. Neri
M. D. Lehnert
H. Dannerbauer
A. Amvrosiadis
P. Andreani
A. J. Baker
A. Beelen
S. Berta
E. Borsato
V. Buat
K. M. Butler
A. Cooray
G. De Zotti
L. Dunne
摘要： We present 101 and 151 GHz ALMA continuum images for 85 fields selected from Herschel observations that have 500 micron flux densities >80 mJy and 250-500 micron colours consistent with z > 2, most of which are expected to be gravitationally lensed or hyperluminous infrared galaxies. Approximately half of the Herschel 500 micron sources were resolved into multiple ALMA sources, but 11 of the 15 brightest 500 micron Herschel sources correspond to individual ALMA sources. For the 37 fields containing either a single source with a spectroscopic redshift or two sources with the same spectroscopic redshift, we examined the colour temperatures and dust emissivity indices. The colour temperatures only vary weakly with redshift and are statistically consistent with no redshift-dependent temperature variations, which generally corresponds to results from other samples selected in far-infrared, submillimetre, or millimetre bands but not to results from samples selected in optical or near-infrared bands. The dust emissivity indices, with very few exceptions, are largely consistent with a value of 2. We also compared spectroscopic redshifts to photometric redshifts based on spectral energy distribution templates designed for infrared-bright high-redshift galaxies. While the templates systematically underestimate the redshifts by ~15%, the inclusion of ALMA data decreases the scatter in the predicted redshifts by a factor of ~2, illustrating the potential usefulness of these millimetre data for estimating photometric redshifts.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
M. Hagimoto
T. J. L. C. Bakx
S. Serjeant
G. J. Bendo
S. A. Urquhart
S. Eales
K. C. Harrington
Y. Tamura
H. Umehata
S. Berta
A. R. Cooray
P. Cox
G. De Zotti
M. D. Lehnert
D. A. Riechers
D. Scott
P. Temi
P. P. van der Werf
C. Yang
A. Amvrosiadis
摘要： We analyse the molecular and atomic emission lines of 71 bright Herschel-selected galaxies between redshifts 1.4 to 4.6 detected by the Atacama Large Millimetre/submillimetre Array. These lines include a total of 156 CO, [C I], and H2O emission lines. For 46 galaxies, we detect two transitions of CO lines, and for these galaxies we find gas properties similar to those of other dusty star-forming galaxy (DSFG) samples. A comparison to photo-dissociation models suggests that most of Herschel-selected galaxies have similar interstellar medium conditions as local infrared-luminous galaxies and high-redshift DSFGs, although with denser gas and more intense far-ultraviolet radiation fields than normal star-forming galaxies. The line luminosities agree with the luminosity scaling relations across five orders of magnitude, although the star-formation and gas surface density distributions (i.e., Schmidt-Kennicutt relation) suggest a different star-formation phase in our galaxies (and other DSFGs) compared to local and low-redshift gas-rich, normal star-forming systems. The gas-to-dust ratios of these galaxies are similar to Milky Way values, with no apparent redshift evolution. Four of 46 sources appear to have CO line ratios in excess of the expected maximum (thermalized) profile, suggesting a rare phase in the evolution of DSFGs. Finally, we create a deep stacked spectrum over a wide rest-frame frequency (220-890 GHz) that reveals faint transitions from HCN and CH, in line with previous stacking experiments.
点击量
待评议
点击量
下载量
评论
