Polarized Line Formation with Lower-level Polarization and Partial Frequency Redistribution
Additional information
Authors
Supriya H.,
Sampoorna M.,
Nagendra K. a.
Type
Journal Article
Year
2016
Language
English
Abstract
In the well-established theories of polarized line formation withpartial frequency redistribution (PRD) for a two-level and two-term atom, it is generally assumed that the lower level of the scattering transition is unpolarized. However, the existence of unexplained spectral features in some lines of the Second Solar Spectrum points toward a need to relax this assumption. There exists a density matrix theory that accounts for the polarization of all the atomic levels, but it is based on the flat-spectrum approximation (corresponding to complete frequency redistribution). In the present paper we propose a numerical algorithm to solve the problem of polarized line formation in magnetized media, which includes both the effects of PRD and the lower level polarization (LLP) for a two-level atom. First we derive a collisionless redistribution matrix that includes the combined effects of the PRD and the LLP. We then solve the relevant transfer equation where J $_ a $ and J $_ b $ represent the total angular momentum quantum numbers of the lower and upper states, respectively. Our studies show that the effects of LLP are significant only in the line core. This leads us to propose a simplified numerical approach to solve the concerned radiative transfer problem.
Journal
Astrophysical Journal
Volume
828
Start page number
84
Keywords
irsol-refereed-scientific-papers
