Non-Zeeman Circular Polarization of Molecular Maser Spectral Lines

Abstract

We apply the anisotropic resonant scattering model developed to explain the presence of non-Zeeman circular polarization signals recently detected in the ${}^{12}\mathrm{CO}\left(J=2\to 1\right)$ and $\left(J=1\to 0\right)$ transitions in molecular clouds to Stokes $V$ spectra of SiO $v=1$ and $v=2$, $\left(J=1\to 0\right)$ masers commonly observed in evolved stars. It is found that the observed antisymmetric "S" and symmetric "$\cup$" or "$\cap$" shaped spectral profiles naturally arise when the maser radiation scatters off populations of foreground molecules located outside the velocity range covered by the background maser radiation. Using typical values for the relevant physical parameters, it is estimated that magnetic field strengths on the order of a few times 15 mG are sufficient to explain the observational results found in the literature.

ApJ Accepted. 19 pages, 4 figures

References in corpus (2)

• Magnetically Aligned Velocity Anisotropy in the Taurus Molecular Cloud
• Probing the Turbulence Dissipation Range and Magnetic Field Strengths in Molecular Clouds

Cited by in corpus (7)

• Magnetic field in IRC+10216 and other C-Rich Evolved Stars
• The Zeeman Effect in the 44 GHz Class I Methanol Maser Line toward DR21(OH)
• Magnetic Field Structure of Orion Source I
• The generation and transformation of polarisation signals in molecular lines through collective anisotropic resonant scattering
• The Zeeman Effect in the 44 GHz Class I Methanol (CH3OH) Maser Line Toward DR21W
• A Curious Case of Circular Polarization in the 25 GHz Methanol Maser Line toward OMC-1
• SiO maser polarization and magnetic field in evolved cool stars