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Class I methanol masers in the Galactic center

Published online by Cambridge University Press:  22 May 2014

L. O. Sjouwerman  and
Y. M. Pihlström
L. O. Sjouwerman
Affiliation:
National Radio Astronomy Observatory, P. O. Box O, 1003 Lopezville Rd., Socorro, NM 87801, USA
Y. M. Pihlström
Affiliation:
Department of Physics and Astronomy, University of New Mexico, MSC07 4220, Albuquerque, NM 87131, USA
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Abstract

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We report on the detection of 36 and 44 GHz Class I methanol (CH3OH) maser emission in the Sagittarius A (Sgr A) complex with the Karl G. Jansky Very Large Array (VLA). These VLA observations show that the Sgr A complex harbors at least three different maser tracers of shocked regions in the radio regime. The 44 GHz masers correlate with the positions and velocities of previously detected 36 GHz CH3OH masers, but less with 1720 MHz OH masers. Our detections agree with theoretical predictions that the densities and temperatures conducive for 1720 MHz OH masers may also produce 36 and 44 GHz CH3OH maser emission. However, many 44 GHz masers do not overlap with 36 GHz methanol masers, suggesting that 44 GHz masers also arise in regions too hot and too dense for 36 GHz masers to form. This agrees with the non-detection of 1720 MHz OH masers in the same area, which are thought to be excited under even cooler and less dense conditions. We speculate that the geometry of the 36 GHz masers outlines the current location of a shock front.

Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 9 , Symposium S303: The Galactic Center: Feeding and Feedback in a Normal Galactic Nucleus , October 2013 , pp. 147 - 149
Copyright
Copyright © International Astronomical Union 2014 

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