POLARIZED LINE FORMATION IN MULTI-DIMENSIONAL MEDIA. V. EFFECTS OF ANGLE-DEPENDENT PARTIAL FREQUENCY REDISTRIBUTION

Journal Article · Fri Feb 10 04:00:00 EST 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/746/1/84· OSTI ID:22011767

Anusha, L S; Nagendra, K N ^[1]

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1. Indian Institute of Astrophysics, Koramangala, 2nd Block, Bangalore 560 034 (India)

The solution of polarized radiative transfer equation with angle-dependent (AD) partial frequency redistribution (PRD) is a challenging problem. Modeling the observed, linearly polarized strong resonance lines in the solar spectrum often requires the solution of the AD line transfer problems in one-dimensional or multi-dimensional (multi-D) geometries. The purpose of this paper is to develop an understanding of the relative importance of the AD PRD effects and the multi-D transfer effects and particularly their combined influence on the line polarization. This would help in a quantitative analysis of the second solar spectrum (the linearly polarized spectrum of the Sun). We consider both non-magnetic and magnetic media. In this paper we reduce the Stokes vector transfer equation to a simpler form using a Fourier decomposition technique for multi-D media. A fast numerical method is also devised to solve the concerned multi-D transfer problem. The numerical results are presented for a two-dimensional medium with a moderate optical thickness (effectively thin) and are computed for a collisionless frequency redistribution. We show that the AD PRD effects are significant and cannot be ignored in a quantitative fine analysis of the line polarization. These effects are accentuated by the finite dimensionality of the medium (multi-D transfer). The presence of magnetic fields (Hanle effect) modifies the impact of these two effects to a considerable extent.

• OSTI ID: 22011767
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 746; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
MAGNETIC FIELDS
ONE-DIMENSIONAL CALCULATIONS
POLARIZATION
SCATTERING
SIMULATION
SOLAR ATMOSPHERE
SOLAR RADIATION
SUN
TWO-DIMENSIONAL CALCULATIONS