http://arxiv.org/abs/1504.07062
We present polarimetric maser observations with the Australia Telescope Compact Array (ATCA) of excited-state hydroxyl (OH) masers. We observed 30 fields of OH masers in full Stokes polarization with the Compact Array Broadband Backend (CABB) at both the 6030 and 6035 MHz excited-state OH transitions, and the 6668-MHz methanol maser transition, detecting 70 sites of maser emission. Amongst the OH we found 112 Zeeman pairs, of which 18 exhibited candidate {\pi} components. This is the largest single full polarimetric study of multiple sites of star formation for these frequencies, and the rate of 16% {\pi} components clearly indicates the {\pi} component exists, and is comparable to the percentage recently found for ground-state transitions. This significant percentage of {\pi} components, with consistent proportions at both ground- and excited-state transitions, argues against Faraday rotation suppressing the {\pi} component emission. Our simultaneous observations of methanol found the expected low level of polarisation, with no circular detected, and linear only found at the less than or equal to 10% level for the brightest sources.
J. Green, J. Caswell and N. McClure-Griffiths
Tue, 28 Apr 15
54/70
Comments: 17 pages (72 pages including appendices), 9 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society
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