A sensitive search for predicted methanol maser transitions with the Australia Telescope Compact Array

Abstract

We have used the Australia Telescope Compact Array (ATCA) to search for a number of centimetre wavelength methanol transitions which are predicted to show weak maser emission towards star formation regions. Sensitive, high spatial and spectral resolution observations towards four high-mass star formation regions which show emission in a large number of class II methanol maser transitions did not result in any detections. From these observations we are able to place an upper limit of <~1300K on the brightness temperature of any emission from the $3_1$A${}^{+}$-$3_1$A${}^{-}$, $17_{-2}$-$18_{-3}$E ($v_t=1$), $12_4$-$13_3$A${}^{-}$, $12_4$-$13_3$A${}^{+}$ and $4_1$A${}^{+}$-$4_1$A${}^{-}$ transitions of methanol in these sources on angular scales of 2 arcseconds. This upper limit is consistent with current models for class II methanol masers in high-mass star formation regions and better constraints than those provided here will likely require observations with next-generation radio telescopes.

Accepted for publication in Publications of the Astronomical Society of Australia, 6 pages, 1 figure, 1 table

References in corpus (4)

• First Parallax Measurements Towards a 6.7 GHz Methanol Maser with the Australian Long Baseline Array - Distance to G339.884-1.259
• Detection of 36 GHz class I methanol maser emission towards NGCS253
• Detection of a methanol megamaser in a major-merger galaxy
• Class I Methanol (CH${}_3$OH) Maser Conditions near Supernova Remnants

Cited by in corpus (3)

• Detection of new methanol maser transitions associated with G358.93-0.03
• Discovery of six new class II methanol maser transitions, including the unambiguous detection of three torsionally excited lines toward G358.931-0.030
• Ammonia masers toward G358.931-0.030