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Title:
X-ray secondary heating and ionization in quasar emission-line clouds
Authors:
Shull, J. M.; van Steenberg, M. E.
Affiliation:
AA(Joint Institute for Laboratory Astrophysics, Boulder, CO), AB(Joint Institute for Laboratory Astrophysics, Boulder, CO)
Publication:
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 298, Nov. 1, 1985, p. 268-274. (ApJ Homepage)
Publication Date:
11/1985
Category:
Astrophysics
Origin:
STI
NASA/STI Keywords:
Emission Spectra, Galactic Nuclei, Interstellar Gas, Photoionization, Quasars, X Ray Astronomy, Astronomical Models, Computational Astrophysics, Electron Energy, Electron Scattering, Radiant Heating, Secondary Emission
DOI:
10.1086/163605
Bibliographic Code:
1985ApJ...298..268S

Abstract

Accurate Monte Carlo computations of the X-ray secondary electron heating, ionization, and excitation of H and He gas in interstellar space and in quasar emission-line clouds, are presented. The fraction of energy deposited in each form is sensitive to the background ionization fraction, x = n(H+)/n(Htot), and can affect the temperature, ionization state, and line emissivities at large depths in X-ray photoionized clouds. Analytic fits are provided for these energy fractions over the range 0.0001-1 for primary electron energies up to many keV. In both broad-line and narrow-line clouds, emission lines sensitive to the energy budget and electron density may be strongly affected.

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