J/A+A/608/A144 Strongly lensed submm galaxies CO spectra (Yang+, 2017)
Molecular gas in the Herschel-selected strongly lensed submillimeter galaxies at
z∼2.4 as probed by multi-J CO lines.
Yang C., Omont A., Beelen A., Gao Y., van der Werf P., Gavazzi R.,
Zhang Z.-Y., Ivison R., Lehnert M., Liu D., Oteo I., Gonzalez-Alfonso E.,
Dannerbauer H., Cox P., Krips M., Neri R., Riechers D., Baker A.J.,
Michalowski M.J., Cooray A., Smail I.
<Astron. Astrophys. 608, A144 (2017)>
=2017A&A...608A.144Y 2017A&A...608A.144Y (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, spectra; Interstellar medium; Millimetric/submm sources
Keywords: galaxies: high-redshift - galaxies: ISM - infrared: galaxies -
submillimeter: galaxies - radio lines: ISM - ISM: molecules
Abstract:
We present the IRAM-30m observations of multiple-J CO (Jup mostly
from 3 up to 8) and [CI](3P2 -> 3P1) ([CI](2-1) hereafter)
line emission in a sample of redshift ∼2-4 submillimeter galaxies
(SMGs). These SMGs are selected among the brightest lensed galaxies
discovered in the Herschel-Astrophysical Terahertz Large Area Survey
(H-ATLAS). 47 CO lines and 7 [CI](2-1) lines have been detected in 15
lensed SMGs. A non-negligible effect of differential lensing is found
for the CO emission lines, which could have caused significant
underestimations of the linewidths, hence of the dynamical masses. The
CO spectral line energy distributions (SLEDs), peaking around
Jup∼5-7, are found to be similar to those of the local
starburst-dominated ultra-luminous infrared galaxies and of the
previously studied SMGs. After correcting for lensing amplification,
we derived the global properties of the bulk of molecular gas in the
SMGs using non-LTE radiative transfer modelling, such as the molecular
gas density nH2∼102.5-104.1cm-3 and the kinetic temperature
Tk∼20-750K. The gas thermal pressure P_{th} ranging from
∼105K/cm3 to 106K/cm3 is found to be correlated with star
formation efficiency. Further decomposing the CO SLEDs into two
excitation components, we find a low-excitation component with
nH2∼102.8-104.6cm-3 and Tk∼20-30K, which is less correlated
with star formation, and a high-excitation one
(nH2∼102.7-104.2cm-3, Tk∼60-400K) which is tightly related
to the on-going star-forming activity. Additionally, tight linear
correlations between the far-infrared and CO line luminosities have
been confirmed for the Jup≥5 CO lines of these SMGs, implying that
these CO lines are good tracers of star formation. The [CI](2-1) lines
follow the tight linear correlation between the luminosities of the
[CI](2-1) and the CO(1-0) line found in local starbursts, indicating
that [CI] lines could serve as good total molecular gas mass tracers
for high-redshift SMGs as well. The total mass of the molecular gas
reservoir, (1-30)x1010M☉, derived based on the CO(3-2) fluxes
and αCO(1-0)=0.8M☉/(K.km/s/pc^2), suggests a typical
molecular gas depletion time tdep∼20-100Myr and a gas to dust mass
ratio δGDR∼30-100 with ∼20%-60% uncertainty for the SMGs. The
ratio between CO line luminosity and the dust mass
L'CO(1-0)/M_{dust} appears to be slowly increasing with redshift for
high-redshift SMGs, which CO need to be further confirmed by a more
complete SMG sample at various redshifts. Finally, through comparing
the linewidth of CO and H2O lines, we find that they agree well in
almost all our SMGs, confirming that the emitting regions of the CO
and H2O lines are co-spatially located.
Description:
The FITS file of the 1D spectra of the CO lines from IRAM-30m
observations are presented. The data files are corresponding to Table 2
in the paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 98 55 List of spectra
sp/* . 55 Individual fits spectra
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See also:
J/A+A/595/A80 : H2O lines reduced spectra in 11 ULIRGs or HyLIRGs (Yang+, 2016)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Right Ascension (J2000)
4- 5 I2 min RAm Right Ascension (J2000)
7- 12 F6.3 s RAs Right Ascension (J2000)
14 A1 --- DE- Declination sign (J2000)
15- 16 I2 deg DEd Declination (J2000)
18- 19 I2 arcmin DEm Declination (J2000)
21- 25 F5.2 arcsec DEs Declination (J2000)
27- 29 I3 --- Nx Number of pixels along X-axis
31 I1 Kibyte size Size of FITS file
33- 54 A22 --- FileName Name of FITS file, in subdirectory sp
56- 98 A43 --- Title Title of the FITS file
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Acknowledgements:
Chentao Yang, yangcht(at)pmo.ac.cn
(End) C. Yang [PMO, China; IAS & IAP, France], P. Vannier [CDS] 18-Sep-2017