J/MNRAS/431/1752 ATLASGAL 6.7GHz methanol masers (Urquhart+, 2013)
ATLASGAL - Environments of 6.7 GHz methanol masers.
Urquhart J.S., Moore T.J.T., Schuller F., Wyrowski F., Menten K.M.,
Thompson M.A., Csengeri T., Walmsley C.M., Bronfman L., Koenig C.
<Mon. Not. R. Astron. Soc. 431, 1752 (2013)>
=2013MNRAS.431.1752U 2013MNRAS.431.1752U
ADC_Keywords: Masers ; Millimetric/submm sources ; Galactic plane
Keywords: Stars: formation - Stars: early-type - Galaxy: structure -
ISM: molecules - ISM: submillimetre.
Abstract:
Using the 870um APEX Telescope large area survey of the Galaxy, we
have identified 577 submillimetre continuum sources with masers from
the methanol multibeam survey in the region 280°<l<20°;
|b|<1.5°. 94 per cent of methanol masers in the region are
associated with submillimetre dust emission. We estimate masses for
∼450 maser-associated sources and find that methanol masers are
preferentially associated with massive clumps. These clumps are
centrally condensed, with envelope structures that appear to be
scale-free, the mean maser position being offset from the peak column
density by 0±4 arcsec. Assuming a Kroupa initial mass function and a
star formation efficiency of ∼30 per cent, we find that over
two-thirds of the clumps are likely to form clusters with masses
>20M☉. Furthermore, almost all clumps satisfy the empirical
mass-size criterion for massive star formation. Bolometric
luminosities taken from the literature for ∼100 clumps range between
∼100 and 106L☉. This confirms the link between methanol masers
and massive young stars for 90 per cent of our sample. The Galactic
distribution of sources suggests that the star formation efficiency is
significantly reduced in the Galactic Centre region, compared to the
rest of the survey area, where it is broadly constant, and shows a
significant drop in the massive star formation rate density in the
outer Galaxy.
Description:
The ATLASGAL (Schuller et al. 2009A&A...504..415S 2009A&A...504..415S) is the first
systematic survey of the inner Galactic plane in the submillimetre
wavelength range. The survey was carried out with the Large APEX
Bolometer Camera (LABOCA), an array of 295 bolometers observing at
870um (345GHz). The 12-m diameter telescope affords an angular
resolution of 19.2 arcsec full width at half-maximum (FWHM).
We have used the same source extraction algorithm and method described
by Contreras et al. (2013, Cat. J/A+A/549/A45) to produce a catalogue
for the currently unpublished 280°<l<330° and
21°<l<60° regions of the survey.
The methanol multibeam (MMB) Survey mapped the Galactic plane for this
maser transition using a 7-beam receiver on the Parkes telescope with
a sensitivity of 0.17Jy/beam. All of these initial maser detections
were followed up at high resolution (∼2 arcsec) with the Australia
Telescope Compact Array (ATCA) to obtain subarcsec positional accuracy
(0.4 arcsec rms).
Table 1 provides derived clump parameters for ATLASGAL clumps
associated with methanol masers identified by the Methanol Multibeam
(MMB) survey: ATLASGAL names, MMB names, offset, aspect ratio,
Y-factor, distance, Galactocentric radius, clump radius, column
density, mass and maser luminosity.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 87 627 Derived clump parameters
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See also:
J/A+A/549/A45 : ATLASGAL Compact Source Catalog: 330<l<21 (Contreras+, 2013)
J/A+A/544/A146 : ATLASGAL cold high-mass clumps with NH3 (Wienen+, 2012)
J/A+A/540/A113 : Starless clumps in ATLASGAL (Tackenberg+, 2012)
J/ApJS/200/5 : 95GHz class I methanol maser survey (Chen+, 2012)
J/ApJ/669/435 : Arecibo Methanol Maser Galactic Plane. II (Pandian+, 2007)
J/A+A/403/1095 : 6.7GHz methanol masers survey of low-mass YSO (Minier+, 2003)
J/A+AS/143/269 : 6.7GHz methanol maser emission survey (Szymczak+, 2000)
J/A+AS/134/115 : Medicina 6.7GHz methanol masers survey (Slysh+ 1999)
J/MNRAS/291/261 : Methanol maser of IRAS-selected sources (Walsh+ 1997)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [AGAL]
5- 18 A14 --- AGAL ATLASGAL designation (LLL.lll+BB.bbb)
20- 22 A3 --- --- [MMB]
23- 36 A14 --- MMB Methanol maser catalogue name (LLL.lll+BB.bbb)
38 I1 --- IR [0/3]? Mid-IR association flag (1)
40- 43 F4.1 arcsec Off [0.2/76.5] Angular offset between the peak of
the sub-mm emission and the maser position
45- 47 F3.1 --- Asp [1/3.4] Clump aspect ratio (2)
49- 53 F5.2 --- Yfac [0.9/25.3] Clump Y-factor (3)
55- 59 F5.2 kpc Dist ? Heliocentric distance
61- 64 F4.1 kpc RGC [1.4/13.7] Galactocentric distance
66- 69 F4.2 pc Rad [0/6]? Effective physical clump radius
71- 75 F5.2 [cm-2] logN(H2) [21.88/24.74] Log of the H2 column density
77- 81 F5.2 [Msun] logM [-1.9/5.5]? Log of the clump mass (4)
83- 87 F5.2 [Jy.kpc2] logL [-1.3/6.4]? Log of isotropic methanol
maser luminosity
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Note (1): MIR flag from Gallaway et al. (2013MNRAS.430..808G 2013MNRAS.430..808G) as follows:
0 = not included
1 = IR bright
2 = IR dark
3 = unclassified
Note (2): Ratio of the semimajor to semiminor sizes of the ATLASGAL source.
Note (3): Ratio of the integrated and peak submillimetre emission (Y-factor).
Note (4): Clump mass derived from the integrated 870um emission assuming
a dust temperature of 20K.
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Acknowledgement:
James Urquhart, jurquhart( at )mpifr-bonn.mpg.de
Max-Planck Institute for Radio Astronomy
History:
* 16-Jul-2013: on-line version of the data
* 26-Nov-2013: table1 corrected (logN(H2), from author)
(End) James Urquhart [MPIFR], Patricia Vannier [CDS] 26-Nov-2013