2000/03/15 by A. -M. Dumont, A. M. Dumont, A. Abrassart +4
Engineering · Materials Science · Physics and Astronomy · #Astrophysics (astro-ph) #Electron and X-Ray Spectroscopy Techniques #FOS: Physical sciences #Nuclear reactor physics and engineering #X-ray Spectroscopy and Fluorescence Analysis #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0003220
17 pages, 21 figures, in press in A&A
arxiv created 2000/03/15 · openalex publication_date 2000/03/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We describe a code designed for hot media (T ≥ a few 104 K), optically thick to Compton scattering. It computes the structure of a plane-parallel slab of gas in thermal and ionization equilibrium, illuminated on one or on both sides by a given spectrum. Contrary to the other photoionization codes, it solves the transfer of the continuum and of the lines in a two stream approximation, without using the local escape probability formalism to approximate the line transfer. We stress the importance of taking into account the returning flux even for small column densities (1022 cm-2), and we show that the escape probability approximation can lead to strong errors in the thermal and ionization structure, as well as in the emitted spectrum, for a Thomson thickness larger than a few tenths. The transfer code is coupled with a Monte Carlo code which allows to take into account Compton and inverse Compton diffusions, and to compute the spectrum emitted up to MeV energies, in any geometry. Comparisons with \sccloudy show that it gives similar results for small column densities. Several applications are mentioned.