Fe L-Shell Density Diagnostics in Theory and Practice
We provide a discussion of the density and photoexcitation sensitivity of the X-ray spectra of Fe L-shell ions (Fe XVII-Fe XXIV) calculated with the Livermore X-ray Spectral Synthesizer, a suite of IDL codes that calculates spectral models of highly charged ions based primarily on HULLAC atomic data. These models are applicable to collisionally ionized laboratory or cosmic plasmas with electron temperatures T{sub e} {approx} 2-45 MK (0.2-4 keV) and electron densities n{sub e} {approx}> 10{sup 11} cm{sup -3}. Potentially useful density diagnostics are identified for Fe XVII and Fe XIX-Fe XXIII, with the most straightforward being the Fe XVII I(17.10 {angstrom})/I(17.05 {angstrom}) line ratio and the Fe XXII I(11.92 {angstrom})/I(11.77 {angstrom}) line ratio. Applying these models to the Chandra X-ray Observatory High Energy Transmission Grating spectrum of the intermediate polar EX Hya, we find that the strength of all the Fe L-shell lines are consistent with electron densities n{sub e} {approx}> 1 x 10{sup 14} cm{sup -3}. Specifically, from the observed Fe XVII I(17.10{angstrom})/I(17.05{angstrom}) line ratio, we infer an electron density n{sub e} {approx}> 2 x 10{sup 14} cm{sup -3} at the 3{sigma} level, while from the observed Fe XXII I(11.92 {angstrom})/I(11.77 {angstrom}) line ratio, we infer n{sub e} = 1.0{sub -0.5}{sup +2.0} x 10{sup 14} cm{sup -3} at the 1{sigma} level and n{sub e} {approx}> 2 x 10{sup 13} cm{sup -3} at the 3{sigma} level.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15011591
- Report Number(s):
- UCRL-PROC-208729; TRN: US200507%%467
- Resource Relation:
- Conference: Presented at: X-ray Diagnostics for Astrophysical Plasmas: Theory, Experiment, and Observation, Cambridge, MA (US), 11/15/2004--11/17/2004; Other Information: PBD: 6 Dec 2004
- Country of Publication:
- United States
- Language:
- English
Similar Records
Plasma Diagnostics in High Resolution X-Ray Spectra of Magnetic Cataclysmic Variables
CHANDRA HIGH-ENERGY TRANSMISSION GRATING SPECTRUM OF AE AQUARII