dc.creator Watson, William D. en_US dc.creator Wiebe, Dmitri S. en_US dc.creator McKinney, Jonathan C. en_US dc.creator Gammie, Charles F. en_US dc.date.accessioned 2006-06-15T20:50:18Z dc.date.available 2006-06-15T20:50:18Z dc.date.issued 2004 en_US dc.identifier 2004-RD-10 en_US dc.identifier.uri http://hdl.handle.net/1811/21283 dc.description Author Institution: University of Illinois; Institute of Astronomy of the RAS; University of Illinois en_US dc.description.abstract We consider astrophysical maser radiation that is created in the presence of mildly supersonic, magnetohydrodynamic (MHD) turbulence. The focus is on the OH masers for which the magnetic field is strong enough that the separations of the Zeeman components are greater than the spectral linebreadths. A longstanding puzzle has been the absence of the Zeeman $\pi$ components and the high circular polarization in the observed spectra of these masers. We first argue that the elongation of eddies along the field that has recently been recognized in MHD turbulence will enhance the optical depth parallel to the magnetic field in comparison with that perpendicular to the magnetic field. We then simulate maser emission with a numerical model of MHD turbulence to demonstrate quantitatively how the intensities of the linearly polarized $\sigma$ components are suppressed and the intensities of the nearly circularly polarized $\pi$ components are enhanced. This effect is also generic in the sense that most spectral lines in MHD turbulence with Mach number $M {\sim} 1$ should have larger optical depth parallel to the magnetic field than perpendicular. The effect is reduced considerably when $M < 1$. The simulations also demonstrate that the velocity and magnetic field variations due to the turbulence can (but do not necessarily) cause one of the $\sigma$ components to be much more intense than the other, as is often observed for mainline OH masers. en_US dc.format.extent 415479 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title A RELATIONSHIP BETWEEN MHD TURBULENCE AND THE POLARIZED SPECTRA OF ASTROPHYSICAL MASERS en_US dc.type article en_US
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