J/ApJS/227/10 CH3OH & OH line emission from Galactic center (Cotton+, 2016)
A large-scale spectroscopic survey of methanol and OH line emission from the
Galactic Center: observations and data.
Cotton W.D., Yusef-Zadeh F.
<Astrophys. J. Suppl. Ser., 227, 10-10 (2016)>
=2016ApJS..227...10C 2016ApJS..227...10C (SIMBAD/NED BibCode)
ADC_Keywords: Masers ; Milky Way ; Radio lines ; Interstellar medium
Keywords: Galaxy: center; ISM: clouds; ISM: molecules; ISM: structure
Abstract:
Class I methanol masers are collisionally pumped and are generally
correlated with outflows in star-forming sites in the Galaxy. Using
the Very Large Array in its A-array configuration, we present a
spectral line survey to identify methanol J=4-1->30E emission at
36.169GHz. Over 900 pointings were used to cover a region 66'x13'
along the inner Galactic plane. A shallow survey of OH at 1612, 1665,
1667, and 1720MHz was also carried out over the area covered by our
methanol survey. We provide a catalog of 2240 methanol masers with
narrow line-widths of ∼1km/s, spatial resolutions of ∼0.14"x0.05", and
rms noises ∼20mJy/beam per channel. Lower limits on the brightness
temperature range from 27000 to 10000000K, showing that the emission
is of non-thermal origin. We also provide a list of 23 OH (1612), 14
OH (1665), 5 OH (1667), and 5 OH (1720MHz) masers. The origin of such
a large number of methanol masers is not clear. Many methanol masers
appear to be associated with infrared dark clouds, though it appears
unlikely that the entire population of these masers traces the early
phase of star formation in the Galactic center.
Description:
The maser observations were centered on the rest frequency of the
collisionally excited class I methanol J=4-1->30E masers (adopted
rest frequency 36.169265GHz). The observations also contained eleven
128MHz sub-bands with 2MHz resolution between 35.3 and 36.5GHz for
continuum calibration. These observations were made in five sessions
between 2014 May 2 and 22.
Hydroxyl observations using L band were made with spectral windows
centered on the rest frequency of the OH lines at 1612, 1665, 1667,
and 1720MHz and were made on 2014 May 31 using the Very Large Array
(VLA) in "A" configuration.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 95 2240 Detected methanol masers
table4.dat 95 23 Detected 1612MHz OH emission
table5.dat 95 14 Detected 1665MHz OH emission
table6.dat 95 5 Detected 1667MHz OH emission
table7.dat 95 5 Detected 1720MHz OH emission
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See also:
J/A+A/563/A68 : CH3OH and H2O Galactic center masers (Chambers+, 2014)
J/ApJ/764/L19 : Methanol emission from the Galactic Center (Yusef-Zadeh+, 2013)
J/other/RAA/10.67 : CH3OH maser sources (Liu+, 2010)
J/ApJ/702/1615 : CH3OH maser survey of EGOs (Cyganowski+, 2009)
J/ApJS/155/149 : CH3OH 70-61 A+ maser sources (Kurtz+, 2004)
J/A+A/391/967 : H2O and SiO masers in the Galactic center (Sjouwerman+, 2002)
J/A+AS/128/35 : New Sample of OH/IR stars (Sjouwerman+ 1998)
J/A+AS/92/43 : Radio Obs. of OH/IR stars close to Gal.Center (Lindqvist+ 1992)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Source identifier
15- 16 I2 h RAh [17] Hour of Right Ascension (J2000)
18- 19 I2 min RAm [43/46] Minute of Right Ascension (J2000)
21- 26 F6.3 s RAs Second of Right Ascension (J2000)
28- 32 F5.3 s e_RAs [0/0.03] Error in RAs (1)
34 A1 --- DE- [-] Sign of the Declination (J2000)
35- 36 I2 deg DEd [28/29] Degree of Declination (J2000)
38- 39 I2 arcmin DEm Arcminute of Declination (J2000)
41- 45 F5.2 arcsec DEs Arcsecond of Declination (J2000)
47- 51 F5.3 arcsec e_DEs [0/0.05] Error in DEs (1)
53- 59 F7.3 deg GLON [0/360] Galactic longitude
61- 66 F6.3 deg GLAT [-0.2/0.2] Galactic latitude
68- 72 I5 mJy Flux [200/74137] Peak flux density at 36.169GHz
74- 76 I3 mJy e_Flux [6/800] Error in Flux (2)
78- 83 F6.1 km/s Vel [-117/179] Center velocity
85- 87 F3.1 km/s Width [0.6/6.3] Line-width
89 A1 --- l_TB Limit flag on TB
91- 95 F5.2 10+5K TB [0.2/99] Brightness temperature
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Note (1): Errors are fitting errors accounting for the effects of correlated
pixel noise (Condon 1997PASP..109..166C 1997PASP..109..166C) and do not include
calibration errors.
Note (2): Derived from the fitted Gaussians in the source finding step
accounting for the effects of correlated noise but do not include
calibration errors.
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Byte-by-byte Description of file: table[4567].dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Source identifier
12- 13 I2 h RAh [17] Hour of right ascension (J2000)
15- 16 I2 min RAm [43/47] Minute of right ascension (J2000)
18- 23 F6.3 s RAs Second of right ascension (J2000)
25- 29 F5.3 s e_RAs [0.01/0.6] RAs uncertainty
31 A1 --- DE- [-] Sign of declination (J2000)
32- 33 I2 deg DEd [28/29] Degree of declination (J2000)
35- 36 I2 arcmin DEm Arcminute of declination (J2000)
38- 42 F5.2 arcsec DEs Arcsecond of declination (J2000)
44- 48 F5.3 arcsec e_DEs [0.01/0.4] DEs uncertainty
50- 55 F6.3 deg GLON [-0.7/0.7] Galactic longitude
57- 62 F6.3 deg GLAT [-0.4/0.2] Galactic latitude
64- 69 I6 mJy Flux [418/143454] Peak flux density
71- 74 I4 mJy e_Flux [33/1236] Flux uncertainty
76- 81 F6.1 km/s Vel [-199/186] Center velocity
83- 85 F3.1 km/s Width [0.7/9] Line width
87- 88 A2 --- Type Spectrum type (only for table 4: "D"=double;
"S"=single peaked spectra)
90 A1 --- l_TB Limit flag on TB
91- 95 F5.2 10+6K TB [0.04/15] Brightness temperature
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 06-Jan-2017