J/MNRAS/500/3050 SSEDIGISM-ATLASGAL in Galactic disc (Urquhart+, 2021)
SEDIGISM-ATLASGAL:
dense gas fraction and star formation efficiency across the Galactic disc.
Urquhart J.S., Figura C., Cross J.R., Wells M.R.A., Moore T.J.T.,
Eden D.J., Ragan S.E., Pettitt A.R., Duarte-Cabral A., Colombo D.,
Schuller F., Csengeri T., Mattern M., Beuther H., Menten K.M., Wyrowski F.,
Anderson L.D., Barnes P.J., Beltran M.T., Billington S.J., Bronfman L.,
Giannetti A., Kainulainen J., Kauffmann J., Lee M.-Y., Leurini S.,
Medina S.-N.X., Montenegro-Montes F.M., Riener M., Rigby A.J.,
Sanchez-Monge A., Schilke P., Schisano E., Traficante A., Wienen M.
<Mon. Not. R. Astron. Soc., 500, 3050-3063 (2021)>
=2021MNRAS.500.3050U 2021MNRAS.500.3050U (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Molecular clouds ; Carbon monoxide ; Spectra, radio
Keywords: surveys, stars: formation - ISM: clouds -
Galaxy: kinematics and dynamics - Galaxy: structure -
submillimetre: ISM
Abstract:
By combining two surveys covering a large fraction of the molecular
material in the Galactic disc, we investigate the role spiral arms
play in the star formation process. We have matched clumps identified
by APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) with
their parental giant molecular clouds (GMCs) as identified by
SEDIGISM, and use these GMC masses, the bolometric luminosities, and
integrated clump masses obtained in a concurrent paper to estimate the
dense gas fractions (DGFgmc=ΣMclump/Mgmc) and the
instantaneous star formation efficiencies (i.e.
SFEgmc=ΣLclump/Mgmc). We find that the molecular material
associated with ATLASGAL clumps is concentrated in the spiral arms
(∼60 per cent found within ±10km/s of an arm). We have searched for
variations in the values of these physical parameters with respect to
their proximity to the spiral arms, but find no evidence for any
enhancement that might be attributable to the spiral arms. The
combined results from a number of similar studies based on different
surveys indicate that, while spiral-arm location plays a role in cloud
formation and HI to H2 conversion, the subsequent star formation
processes appear to depend more on local environment effects. This
leads us to conclude that the enhanced star formation activity seen
towards the spiral arms is the result of source crowding rather than
the consequence of any physical process.
Description:
ATLASGAL (Schuller et al., 2009A&A...504..415S 2009A&A...504..415S; Beuther et al.
2012ApJ...747...43B 2012ApJ...747...43B) is an unbiased 870-um submillimetre survey
covering 420deg2 of the inner Galactic plane. It was specifically
designed to identify an unbiased sample of dense, high-mass clumps
that includes examples of all embedded evolutionary stages in the
formation of massive stars. This survey has identified ∼10000
clumps distributed across the inner Galactic plane (Contreras et al.
2013A&A...549A..45C 2013A&A...549A..45C, Cat. J/A+A/549/A45; Csengeri et al.
2014A&A...565A..75C 2014A&A...565A..75C, Cat. J/A+A/565/A75; Urquhart et al.
2014A&A...568A..41U 2014A&A...568A..41U, Cat. J/A+A/568/A41); these clumps have sizes of
∼0.5pc and masses ∼500M☉ (Urquhart et al. 2018MNRAS.473.1059U 2018MNRAS.473.1059U,
Cat. J/MNRAS/473/1059).
The SEDIGISM survey (Schuller et al. 2017A&A...601A.124S 2017A&A...601A.124S, Cat.
J/A+A/601/A124 - hereafter Paper I) utilized the 12-m Atacama
Pathfinder Experiment (APEX; Guesten et al. 2006A&A...454L..13G 2006A&A...454L..13G)
submillimetre telescope between 2013 and 2015 to observe the J=2-1
transitions of the 13CO and C18O isotopologues and 10 other
significant molecular tracers, including shock tracers (such as SiO
and SO) and dense gas tracers (H2CO, CH3OH, CH3CN).
There are 5754 clumps in the ATLASGAL CSC (Contreras et al.
2013A&A...549A..45C 2013A&A...549A..45C, Cat. J/A+A/549/A45; Urquhart et al.
2014A&A...568A..41U 2014A&A...568A..41U, Cat. J/A+A/568/A41) that are located inside the
region of the Galactic plane covered by SEDIGISM. We extracted spectra
for the 13CO and C18O (2-1) transitions towards all of these
positions by integrating the emission within a 30 arcsec aperture
centred on the peak 870um dust emission. Inspection of the extracted
13CO data revealed that approximately 10 per cent (606) of the
spectra are affected by poor baselines and/or very broad emission
features (>30km/s; all of the latter are found towards the Galactic
Centre). We have excluded these from our analysis as they are unlikely
to provide any reliable information for the clumps.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 60 18710 Fitted Gaussian parameters to CO spectra
extracted towards ATLASGAL clumps
table2.dat 189 5148 *Assigned velocities and derived physical
parameters for the ATLASGAL clumps
table3.dat 40 1695 Properties of matched SEDIGISM GMCs
fig3/* . 10296 Figures of spectra (eps and png versions)
sp13co/* . 5148 13CO fits spectra
spc18o/* . 5148 C18O fits spectra
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Note on table2.dat: The clumps' SFEs are taken directly from Urquhart et al.
(2018MNRAS.473.1059U 2018MNRAS.473.1059U, Cat. J/MNRAS/473/1059).
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See also:
J/A+A/549/A45 : ATLASGAL Compact Source Catalog: 330<l<21 (Contreras+, 2013)
J/A+A/565/A75 : ATLASGAL dust condensations in Galactic plane
(Csengeri+, 2014)
J/A+A/568/A41 : ATLASGAL Compact Source Catalog: 280<l<60 (Urquhart+, 2014)
J/A+A/601/A124 : Clouds in SEDIGISM science demonstration field
(Schuller+, 2017)
J/MNRAS/473/1059 : Complete sample of Galactic clump properties
(Urquhart+, 2018)
https://atlasgal.mpifr-bonn.mpg.de/cgi-bin/ATLASGAL_DATABASE.cgi :
ATLASGAL survey web server
https://sedigism.mpifr-bonn.mpg.de/cgi-bin-seg/SEDIGISM_DATABASE.cgi :
SEDIGISM survey web server
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- CSC ATLASGAL name
20- 23 A4 -- Trans CO Transition
25- 29 F5.2 K TA* Antenna temperature
31- 34 F4.2 K e_TA* Antenna temperature error
36- 42 F7.2 km/s VLSR LSR velocity
44- 48 F5.2 km/s e_VLSR LSR velocity error
50- 54 F5.2 km/s FWHM Full width at half-maximum
56- 60 F5.2 km/s e_FWHM Full width at half-maximum error
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- CSC ATLASGAL Name
20- 23 A4 --- Trans CO Transition
25- 31 F7.1 km/s VLSR ?=-999.0 ATLASGAL LSR velocity
33- 36 F4.1 K 13COTA* ?=- 13CO antenna temperature
38- 41 F4.1 K C18OTA* ?=- C18O antenna temperature
43- 47 F5.2 km/s 13COFWHM ?=- 13CO full width at half-maximum
49- 54 F6.2 --- L/M ?=- Lbol/Mclump light-to-mass ratio
56- 60 F5.2 kpc Rgc Galactocentric radius
62- 78 A17 --- GMC SEDIGISM name
80-113 A34 --- Fig3 Name of the spectrum image (png) in
subdirectory fig3 (1)
115-151 A37 --- SP13CO Name of the 13CO spectrum file in
subdirectory sp13co
153-189 A37 --- SPC18O Name of the C18O spectrum file in
subdirectory spc18o
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Note (1): 13CO (black line) and C18O (grey) spectra from the ATLASGAL
survey; the former is offset by 2K from zero intensity. The results of the
automatic Gaussian fitting are overlaid in red and blue and the velocity
assigned to the clump is indicated by the green vertical dash-dotted line.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- GMC SEDIGISM Name
19- 22 F4.1 km/s FWHM Full width at half-maximum
24- 28 F5.2 kpc RGC Galactocentric distance
30- 34 F5.2 --- DGFcloud ?=- Dense gas fraction, ΣMclump/Mgmc
36- 40 F5.2 --- SFEcloud ?=- Instantaneous star formation efficiency,
ΣLclump/Mgmc
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 20-Sep-2022