Detection of 36 GHz class I methanol maser emission towards NGCS253

Abstract

We have used the Australia Telescope Compact Array (ATCA) to search for emission from the $4_{-1}\to 3_{0}E$ transition of methanol (36.2 GHz) towards the center of the nearby starburst galaxy NGC253. 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 arcsec, has a full-width half maximum (FWHM) line width of < 30 km s${}^{-1}$, and an isotropic luminosity orders of magnitude larger than that observed in any Galactic star formation regions. 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 NGC253 has more than an order of magnitude higher isotropic luminosity than the widespread emission recently detected towards the center of the Milky Way. If emission from this transition scales with nuclear star formation rate then it may be detectable in the central regions of many starburst galaxies. Detection of methanol emission in ultra-luminous infra-red galaxies (ULIRGs) would open up a new tool for testing for variations in fundamental constants (in particular the proton-to-electron mass ratio) on cosmological scales.

Accepted for publication in ApJ Letters, 5 pages, 2 figures

References in corpus (14)

• The ACS Nearby Galaxy Survey Treasury
• The present-day star formation rate of the Milky-Way determined from Spitzer detected young stellar objects
• A Class I and Class II Methanol Maser Survey of Extended Green Objects (EGOs) from the GLIMPSE Survey
• A 2 mm spectral line survey of the starburst galaxy NGC 253
• ALMA Reveals the Molecular Medium Fueling the Nearest Nuclear Starburst
• Class I methanol masers in the outflow of IRAS 16547-4247
• New insights on the dense molecular gas in NGC253 as traced by HCN and HCO+
• ALMA observations of 99 GHz free-free and H40$\alpha$ line emission from star formation in the centre of NGC 253
• An ALMA Early Science survey of molecular absorption lines toward PKS1830-211 -- Analysis of the absorption profiles
• The Sub-parsec Scale Radio Properties of Southern Starburst Galaxies. I. Supernova Remnants, the Supernova Rate, and the Ionised Medium in the NGC 253 Starburst
• The Circumnuclear Molecular Gas in the Seyfert Galaxy NGC4945
• Detection of 36 GHz class I methanol maser emission towards NGCS253
• Detection of a methanol megamaser in a major-merger galaxy
• 6.7 GHz methanol absorption toward the Seyfert 2 galaxy NGC 3079

Cited by in corpus (11)

• Online Database of Class I Methanol Masers
• Survey of Water and Ammonia in Nearby galaxies (SWAN): Resolved Ammonia Thermometry, Water and Methanol Masers in the Nuclear Starburst of NGC 253
• Detection of 36 GHz class I methanol maser emission towards NGCS253
• Detection of a methanol megamaser in a major-merger galaxy
• Class I methanol masers in NGC253: Alcohol at the end of the bar
• A study of submillimeter methanol absorption toward PKS1830-211: Excitation, invariance of the proton-electron mass ratio, and systematics
• MALT-45: A 7mm survey of the southern Galaxy - II. ATCA follow-up observations of 44GHz class I methanol masers
• Astrophysical constraints on the proton-to-electron mass ratio with FAST
• 36 GHz methanol lines from nearby galaxies: maser or quasi-thermal emission?
• Variability in extragalactic class I methanol masers: New maser components toward NGC4945 and NGC253
• A sensitive search for predicted methanol maser transitions with the Australia Telescope Compact Array