Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/5409
Title: OH Maser sources in W49N: probing differential anisotropic scattering with Zeeman pairs
Authors: Deshpande, A.A.
Goss, W.M.
Mendoza-Torres, Jose E.
Keywords: masers
ISM: molecules
magnetic fields
radio lines
Issue Date: Jul-2012
Publisher: Cambridge University Press
Citation: Proceedings of IAU Symposium No. 287, held on 29 Jan - 3 Feb, 2012.
Abstract: Our analysis of a VLBA 12-hour synthesis observations of the OH masers in W49N has provided detailed high angular-resolution images of the maser sources, at 1612, 1665 and 1667 MHz. The images, of several dozens of spots, reveal anisotropic scatter broadening; with typical sizes of a few tens of milli-arc-seconds and axial ratios between 1.5 to 3. The image position angles oriented perpendicular to the galactic plane are interpreted in terms of elongation of electron-density irregularities parallel to the galactic plane, due to a similarly aligned local magnetic field. However, we find the apparent angular sizes on the average a factor of 2.5 less than those reported by Desai et al., indicating significantly less scattering than inferred earlier. The average position angle of the scattered broadened images is also seen to deviate significantly (by about 10 degrees) from that implied by the magnetic field in the Galactic plane. More intriguingly, for a few Zeeman pairs in our set, we find significant differences in the scatter broadened images for the two hands of polarization, even when apparent velocity separation is less than 0.1 km/s. Here we present the details of our observations and analysis, and discuss the interesting implications of our results for the intervening anisotropic magneto-ionic medium, as well as a comparison with the expectations based on earlier work.
Description: Restricted Access.
URI: http://hdl.handle.net/2289/5409
ISSN: 9781107032842
Alternative Location: http://adsabs.harvard.edu/abs/2012IAUS..287..470D
http://arxiv.org/abs/1203.3138
Copyright: 2012 Cambridge University Press
Appears in Collections:Research Papers (A&A)

Files in This Item:
File Description SizeFormat 
2012_IAU_V287_p470.pdf
  Restricted Access
Restricted Access224.07 kBAdobe PDFView/Open Request a copy


Items in RRI Digital Repository are protected by copyright, with all rights reserved, unless otherwise indicated.