J/MNRAS/446/3461 6.7-GHz methanol masers-dust associations (Urquhart+, 2015)
The almost ubiquitous association of 6.7-GHz methanol masers with dust.
Urquhart J.S., Moore T.J.T., Menten K.M., Konig C., Wyrowski F.,
Thompson M.A., Csengeri T., Leurini S., Eden D.J.
<Mon. Not. R. Astron. Soc., 446, 3461-3477 (2015)>
=2015MNRAS.446.3461U 2015MNRAS.446.3461U (SIMBAD/NED BibCode)
ADC_Keywords: Masers ; Molecular clouds ; Morphology
Keywords: stars: early-type - stars: formation - ISM: clouds - Galaxy: structure
Abstract:
We report the results of 870µm continuum observations, using the
Large APEX Bolometer Camera, towards 77 class-II, 6.7-GHz methanol
masers identified by the Methanol MultiBeam (MMB) survey to map the
thermal emission from cool dust towards these objects. These data
complement a study of 630 methanol masers associated with compact
dense clumps identified from the APEX Telescope Large Area Survey of
the Galaxy (ATLASGAL) survey. Compact dust emission is detected
towards 70 sources, which implies a dust-association rate of 99 per
cent for the full MMB catalogue. Evaluation of the derived dust and
maser properties leads us to conclude that the combined sample
represents a single population tracing the same phenomenon. We find
median clump masses of a few 103M☉ and that all but a handful
of sources satisfy the mass-size criterion required for massive star
formation. This study provides the strongest evidence of the almost
ubiquitous association of methanol masers with massive, star-forming
clumps. The fraction of methanol-maser associated clumps is a factor
of ∼2 lower in the outer Galaxy than the inner Galaxy, possibly a
result of the lower metallicity environment of the former. We find no
difference in the clump-mass and maser-luminosity distributions of the
inner and outer Galaxy. The maser-pumping and clump formation
mechanisms are therefore likely to be relatively invariant to Galactic
location. Finally, we use the ratio of maser luminosity and clump mass
to investigate the hypothesis that the maser luminosity is a good
indicator of the evolutionary stage of the embedded source, however,
we find no evidence to support this.
Description:
To complement the sample of inner Galaxy methanol-maser associated
clumps identified in Paper I (Urquhart et al., 2013MNRAS.431.1752U 2013MNRAS.431.1752U,
Cat. J/MNRAS/431/1752), we have made submillimetre-continuum
observations towards 77 MMB sources that either lie outside the region
covered by the ATLASGAL survey (i.e. 180°<l<280° or
|b|>1.5°) or were not found to be associated with an ATLASGAL
source.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 56 72 Observed field positions and map sensitivity
table2.dat 100 303 The submillimetre sources detected in the
reduced LABOCA maps
table4.dat 88 70 Derived clump parameters
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See also:
VIII/96 : 6-GHz methanol multibeam maser catalogue, MMB
(Caswell+, 2010-12)
J/MNRAS/431/1752 : ATLASGAL 6.7GHz methanol masers (Urquhart+, 2013)
J/A+A/568/A41 : ATLASGAL Compact Source Catalog: 280<l<60 (Urquhart+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Field Field name (GLLL.lll+BB.bbb)
17- 18 I2 h RAh Right ascension (J2000)
20- 21 I2 min RAm Right ascension (J2000)
23- 27 F5.2 s RAs Right ascension (J2000)
29 A1 --- DE- Declination sign (J2000)
30- 31 I2 deg DEd Declination (J2000)
33- 34 I2 arcmin DEm Declination (J2000)
36- 39 F4.1 arcsec DEs Declination (J2000)
41- 44 F4.1 arcmin IntTime Intergation time
46- 48 F3.1 mm PWV Precipitable water vapour
50- 52 I3 mJy rms rms noise (in mJy/beam)
54- 56 A3 --- ATLASGAL [yes/no ] indicates whether a field was inside
or outside the ATLASGAL survey region
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Name derived from Galactic coordinates of the
maximum intensity in the source
(GLLL.lll+BB.bbb)
17- 23 F7.3 deg GLONmax Galactic longitude of maximum intensity in the
catalogue source
25- 31 F7.3 deg GLATmax Galactic latitude of maximum intensity in the
catalogue source
33- 39 F7.3 deg GLON Galactic longitude of emission centroid
41- 47 F7.3 deg GLAT Galactic latitude of emission centroid
49- 50 I2 arcsec amaj Souce semi-major axis
52- 53 I2 arcsec bmin Souce semi-minor axis
55- 57 I3 deg PA Source position angle (measured anticlockwise
from Galactic north)
59- 64 F6.1 arcsec Reff ?=-999 Effective radius of source
66- 71 F6.2 Jy Speak Peak flux density at 870um (in Jy/beam)
73- 76 F4.2 Jy e_Speak rms uncertainty on Speak
78- 84 F7.2 Jy Sint ?=-999 Integrated flux density at 870um
86- 90 F5.2 Jy e_Sint ?=-9 rms uncertainty on Sint
92- 93 I2 --- Flag SExtractor detection flag (see Bertin & Arnouts
1996A&AS..117..393B 1996A&AS..117..393B notes on these flags)
95-100 F6.1 --- SNR Signal-to-noise ratio (1)
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Note (1): values for sources with peak flux below 6σ detection should
not be used blindly.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [MMB]
4- 17 A14 --- MMB MMB source name (LLL.lll+BB.bbb)
19- 33 A15 --- submm submm source name (GLLL.lll+BB.bbb)
35- 38 F4.1 arcsec Offset Angular offset between the peak of the
submillimetre emission and the maser position
40- 42 F3.1 --- Aspect Aspect ratio (ratio of the semi-major to
semi-minor sizes of the ATLASGAL source)
44- 48 F5.2 --- Y-factor Ratio of the integrated and peak
submillimetre emission
50- 54 F5.1 kpc Dist ?=-99 Heliocentric distance
56- 57 I2 --- r_Dist ?=- Heliocentric distance reference (1)
59- 63 F5.1 kpc RGC ?=-99 Galactocentric distance
65- 70 F6.2 pc Rad ?=-99 Effective physical radius
72- 76 F5.2 [cm-2] logNH2 H2 column density
78- 82 F5.2 [Msun] logMclump ?=-9 Clump mass derived from the integrated
870um emission assuming a dust temperature
of 20K
84- 88 F5.2 [Jy/kpc2] logLMMB ?=-9 Isotropic methanol-maser luminosity
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Note (1): References as follows:
1 = Green & McClure-Griffiths (2011MNRAS.417.2500G 2011MNRAS.417.2500G)
2 = this paper
3 = Niinuma et al. (2011PASJ...63....9N 2011PASJ...63....9N)
4 = Oh et al. (2010PASJ...62..101O 2010PASJ...62..101O)
5 = Kawamura et al. (1998ApJS..117..387K 1998ApJS..117..387K)
6 = Honma et al. (2007PASJ...59..889H 2007PASJ...59..889H)
7 = Menten et al. (2007A&A...474..515M 2007A&A...474..515M)
8 = Reid et al. (2009ApJ...700..137R 2009ApJ...700..137R)
9 = Netterfield et al. (2009ApJ...707.1824N 2009ApJ...707.1824N, Cat. J/ApJ/707/1824)
10 = Moises et al. (2011MNRAS.411..705M 2011MNRAS.411..705M, Cat. J/MNRAS/411/705)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 29-Jun-2015