X-ray spectral signatures of photoionized plasmas. [Astrophysics]

Journal Article · Thu Feb 01 04:00:00 EST 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/185662· OSTI ID:6917591

Liedahl, D A; Kahn, S M; Osterheld, A L; Goldstein, W H ^[1]

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1. California Univ., Berkeley (USA) Lawrence Livermore National Laboratory, CA (USA)

Plasma emission codes have become a standard tool for the analysis of spectroscopic data from cosmic X-ray sources. However, the assumption of collisional equilibrium, typically invoked in these codes, renders them inapplicable to many important astrophysical situations, particularly those involving X-ray photoionized nebulae. This point is illustrated by comparing model spectra which have been calculated under conditions appropriate to both coronal plasmas and X-ray photoionized plasmas. It is shown that the (3s-2p)/(3d-2p) line ratios in the Fe L-shell spectrum can be used to effectively discriminate between these two cases. This diagnostic will be especially useful for data analysis associated with AXAF and XMM, which will carry spectroscopic instrumentation with sufficient sensitivity and resolution to identify X-ray photoionized nebulae in a wide range of astrophysical environments. 25 refs.

• OSTI ID: 6917591
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 350; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
640105 -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BINARY STARS
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
GALAXY CLUSTERS
IONIZATION
NEBULAE
PHOTOIONIZATION
PLASMA
SPECTRA
STAR ACCRETION
STAR EVOLUTION
STARS
X-RAY SPECTRA