Accurate rest frequencies of methanol maser and dark cloud lines

Müller, H. S. P.; Menten, K. M.; Mäder, H.

doi:10.1051/0004-6361:20041384

Cited by 105 publications

(107 citation statements)

References 49 publications

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“…r max−obs , we define a minimum luminosity for all detected masers. For a detection limit of 1 Jy over 0.2 km s −1 or 5.56 kHz at the rest frequency of 6.668519 GHz (Müller et al 2004), we get minimum luminosities of the masers of 2.85 × 10 −6 , 1.91 × 10 −7 and 7.33 × 10 −8 L for r max−obs equal to 40.5, 10.5 and 6.5 kpc, respectively.…”

Section: Luminosity Distribution Of Methanol Masers 221 Step 1: Eqmentioning

confidence: 76%

A general catalogue of 6.7 GHz methanol masers

Pestalozzi

Chrysostomou

Collett

et al. 2006

A&A

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Context. Methanol masers at 6.7 GHz are recognised markers of high-mass star formation regions. The study of their distribution in the Galaxy gives important insights into the star formation activity of the Milky Way. We present a statistical analysis on the General Catalogue of 6.7 GHz methanol masers in the Galaxy with the aim of extracting global properties of the masers. Aims. We provide constraints on the luminosity function of 6.7 GHz methanol masers and on their total number in the Galaxy. Methods. We model the spatial distribution of the masers in the Milky Way by using their distribution in galactocentric distance which is unambiguous once a rotation curve for the Galaxy is assumed. This is the starting point for determining the luminosity function of the masers.Results. The luminosity function of 6.7 GHz methanol masers is modelled as a power-law with sharp cutoffs and having an index lying between −1.5 and −2. We also predict the number of detections of methanol masers assuming different sensitivity limits in the observations.

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Section: Luminosity Distribution Of Methanol Masers 221 Step 1: Eqmentioning

confidence: 76%

A general catalogue of 6.7 GHz methanol masers

Pestalozzi

Chrysostomou

Collett

et al. 2006

A&A

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“…All data were reduced using the ATNF (Australia Telescope National Facility) Spectral Analysis Package (ASAP). A rest frequency of 12.178 597 GHz (Müller, Menten & Mäder 2004) was adopted and all velocities given are with respect to LSR. Detection (5σ ) limits are listed in Table 1 and are chiefly in the range 0.55-0.80 Jy (note that the noise in the detections will also fall in this range).…”

Section: O B S E Rvat I O N S a N D Data R E D U C T I O Nmentioning

confidence: 99%

12.2-GHz methanol maser MMB follow-up catalogue – IV. Longitude range 20°–60°

Breen

Ellingsen

Caswell

et al. 2016

Mon. Not. R. Astron. Soc.

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This is the fourth and final instalment of a series of catalogues presenting 12.2-GHz methanol maser observations made towards each of the 6.7-GHz methanol masers detected in the Methanol Multibeam (MMB) survey. This final portion of the survey covers the 20 • -60 • longitude range, increasing the 12.2-GHz follow-up range to the full MMB coverage of 186 • ≥ l ≤ 60 • and |b| ≤ 2 • . Towards a total of 260 6.7-GHz MMB methanol masers (we were unable to observe five of the MMB sources in this longitude range) we detect 116 12.2-GHz masers counterparts, 64 of which were discovered in this survey. Including data from the literature, we find that there are 12.2-GHz methanol masers towards 47.1 per cent of the 6.7-GHz methanol masers in this portion of the Galaxy. Across the entire MMB survey range, we find a detection rate of 45.3 per cent. We find that the detection rate of 12.2-GHz methanol masers as a function of Galactic longitude is not uniform and there is an excess of masers with broad velocity ranges at longitudes near 30 • and 330 • . Comparing the occurrence of 12.2-GHz methanol masers with MMB-targeted CO observations has shown that those outflows associated with a 12.2-GHz source have a larger average dynamical time-scale than those associated with only 6.7-GHz methanol masers, supporting the notion that the 12.2-GHz masers are associated with a later phase of high-mass star formation.

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“…Four CH3OH lines were targeted, the 20 − 3−1 E, 10 − 00 A + and E, and 10−2−1 E transitions at 12.178597(4) GHz, 48.3724558(7) GHz, 48.376892(10) GHz, and 60.531489(10) GHz, respectively (for the line frequencies, see Müller et al 2004, and references therein). These are redshifted to observing frequencies of ≈ 6.46 GHz (Cband), 25.65 GHz (two lines; K-band) and 32.10 GHz (Ka-band), respectively.…”

Section: Observations Data Analysis and Spectramentioning

confidence: 99%

“…The sensitivity of the VLA C-band spectrum in this transition is a factor of ≈ 1.8 better than that of the best earlier spectra. Breckenridge & Kukolich 1995;Müller et al 2004) and the sensitivity coefficents to changes in µ (Jansen et al 2011). The redshifts of the 48.372 and 48.377 GHz lines were tied together in the fit (as these transitions have the same Kµ value), as were the column densities in the 60.531 and 48.377 GHz lines (both E-type transitions).…”

Section: Observations Data Analysis and Spectramentioning

confidence: 99%

Constraints on changes in the proton–electron mass ratio using methanol lines

Kanekar

Ubachs

Menten

et al. 2015

Monthly Notices of the Royal Astronomical Society: Letters

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We report Karl G. Jansky Very Large Array (VLA) absorption spectroscopy in four methanol (CH 3 OH) lines in the z = 0.88582 gravitational lens towards PKS1830−211. Three of the four lines have very different sensitivity coefficients K µ to changes in the proton-electron mass ratio µ; a comparison between the line redshifts thus allows us to test for temporal evolution in µ. We obtain a stringent statistical constraint on changes in µ by comparing the redshifted 12.179 GHz and 60.531 GHz lines, [∆µ/µ] 1.1 × 10 −7 (2σ) over 0 < z 0.88582, a factor of ≈ 2.5 more sensitive than the best earlier results. However, the higher signal-to-noise ratio (by a factor of ≈ 2) of the VLA spectrum in the 12.179 GHz transition also indicates that this line has a different shape from that of the other three CH 3 OH lines (at > 4σ significance). The sensitivity of the above result, and that of all earlier CH 3 OH studies, is thus likely to be limited by unknown systematic errors, probably arising due to the frequency-dependent structure of PKS1830−211. A robust result is obtained by combining the three lines at similar frequencies, 48.372, 48.377 and 60.531 GHz, whose line profiles are found to be in good agreement. This yields the 2σ constraint [∆µ/µ] 4 × 10 −7 , the most stringent current constraint on changes in µ. We thus find no evidence for changes in the proton-electron mass ratio over a lookback time of ≈ 7.5 Gyrs.

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Accurate rest frequencies of methanol maser and dark cloud lines

Cited by 105 publications

References 49 publications

A general catalogue of 6.7 GHz methanol masers

A general catalogue of 6.7 GHz methanol masers

12.2-GHz methanol maser MMB follow-up catalogue – IV. Longitude range 20°–60°

Constraints on changes in the proton–electron mass ratio using methanol lines

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