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Title: DETECTION OF 36 GHz CLASS I METHANOL MASER EMISSION TOWARD NGC 253

We have used the Australia Telescope Compact Array to search for emission from the 4{sub –1} → 3{sub 0} E transition of methanol (36.2 GHz) toward the center of the nearby starburst galaxy NGC 253. Two regions of emission were detected, offset from the nucleus along the same position angle as the inner spiral arms. The emission is largely unresolved on a scale of 5'', has a FWHM line width of <30 km s{sup –1}, and an isotropic luminosity orders of a magnitude larger than that observed in any Galactic star formation region. These characteristics suggest that the 36.2 GHz methanol emission is most likely a maser, although observations with higher angular and spectral resolution are required to confirm this. If it is a maser, this represents the first detection of a class I methanol maser outside the Milky Way. The 36.2 GHz methanol emission in NGC 253 has more than an order of magnitude higher isotropic luminosity than the widespread emission recently detected toward the center of the Milky Way. If emission from this transition scales with the nuclear star formation rate, then it may be detectable in the central regions of many starburst galaxies. Detection of methanol emission in ultra-luminous infrared galaxies wouldmore » open up a new tool for testing for variations in fundamental constants (particularly the proton-to-electron mass ratio) on cosmological scales.« less
Authors:
 [1] ; ; ; ; ;  [2] ;  [3]
  1. School of Physical Sciences, University of Tasmania, Hobart, Tasmania (Australia)
  2. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 (China)
  3. CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia)
Publication Date:
OSTI Identifier:
22365441
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 790; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ELECTRONS; FUNDAMENTAL CONSTANTS; GHZ RANGE; LINE WIDTHS; LUMINOSITY; MASERS; METHANOL; MILKY WAY; PROTONS; RESOLUTION; STAR CLUSTERS; STAR EVOLUTION; STARS; TELESCOPES