Characterizing maser polarization: effects of saturation, anisotropic pumping and hyperfine structure

Abstract

The polarization of masers contains information on the magnetic field strength and direction of the regions they occur in. Many maser polarization observations have been performed over the last 30 years. However, versatile maser polarization models that can aide in the interpretation of these observations are not available. We aim to develop a program suite that can compute the polarization by a magnetic field of any non-paramagnetic maser specie at arbitrarily high maser saturation. Furthermore, we aim to investigate the polarization of masers by non-Zeeman polarizing effects. We aim to present a general interpretive structure for maser polarization observations. We expand existing maser polarization theories of non-paramagnetic molecules and incorporate these in a numerical modeling program suite. We present a modeling program that CHAracterizes Maser Polarization (CHAMP) that can examine the polarization of masers of arbitrarily high maser saturation and high angular momentum. Also, hyperfine multiplicity of the maser-transition can be incorporated. The user is able to investigate non-Zeeman polarizing mechanisms such as anisotropic pumping and polarized incident seed radiation. We present an analysis of the polarization of v = 1 SiO masers and the 22 GHz water maser. We comment on the underlying polarization mechanisms, and also investigate non-Zeeman effects. We identify the regimes where different polarizing mechanisms will be dominant and present the polarization characteristics of the SiO and water masers. From the results of our calculations, we identify markers to recognize alternative polarization mechanisms.

67 pages, 27 figures. Accepted to be published in A&A

References in corpus (4)

• A magnetically collimated jet from an evolved star
• Extragalactic Zeeman Detections in OH Megamasers
• A new probe of magnetic fields during high-mass star formation: Zeeman splitting of 6.7 GHz methanol masers
• Non-Zeeman Circular Polarization of Molecular Maser Spectral Lines

Cited by in corpus (9)

• PORTAL--three-dimensional polarized (sub)millimeter line radiative transfer
• High Sensitivity Observations of the Water Megamasers of NGC 1068: Precise Astrometry and Detailed Kinematics
• Magnetic Field Structure of Orion Source I
• Mapping circumstellar magnetic fields of late-type evolved stars with the Goldreich-Kylafis effect: CARMA observations at $\lambda 1.3$ mm of R Crt and R Leo
• Tracing the large-scale magnetic field morphology in protoplanetary disks using molecular line polarization
• Polarized Maser Emission with In-Source Faraday Rotation
• SiO maser polarization and magnetic field in evolved cool stars
• Polarization properties of methanol masers
• Molecular line polarisation from the circumstellar envelopes of Asymptotic Giant Branch stars