1. X-ray Line Emission from Optically-Thick Astrophysical Media.
- Author
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Sako, Masao and Watanabe, Shin
- Subjects
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SPECTRUM analysis , *HEAT radiation & absorption , *EINSTEIN-Podolsky-Rosen experiment , *X-ray binaries , *SPECTRUM analysis instruments , *EMISSION control , *ASTROPHYSICS - Abstract
Radiative transfer effects are capable of producing line spectra that differ markedly from those emitted from an optically-thin medium. Line photons that travel through an optically-thick medium may suffer multiple non-coherent scatterings, which can alter substantially the profiles of the emergent spectrum. Line transfer can also affect the emergent line intensities through destructive processes in which the energy is either re-radiated through other discrete transitions or is used in heating the ambient plasma. There are numerous astrophysical scenarios where transfer of X-ray lines may be relevant, including ionized surface layers of accretion disks, stellar winds in X-ray binaries, outflowing regions in active galactic nuclei, circumstellar environment of cosmic gamma-ray bursts, and even in the intergalactic medium of clusters of galaxies. Here, we focus on three specific transfer problems that are important for modeling and interpreting astrophysical X-ray spectra acquired with the grating spectrometers on board the Chandra and XMM-Newton observatories: (1) Compton scattering of emission lines, (2) fluorescent line emission from L-shell ions, and (3) overlap of two or more lines. We describe the relevant atomic processes, spectroscopic issues, and useful computational methods for solving these types of problems. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]
- Published
- 2004
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