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Photoionization Modeling: the K Lines and Edges of Iron

Photoionization Modeling: the K Lines and Edges of Iron. P. Palmeri (UMH-Belgium) T. Kallman (GSFC/NASA-USA) C. Mendoza & M. Bautista (IVIC-Venezuela) J. Krolik (JHU-USA). Plan. Introduction Atomic Data Photoionized Plasma Modeling Conclusions. Serlemitsos, et al, 1973. Introduction.

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Photoionization Modeling: the K Lines and Edges of Iron

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  1. Photoionization Modeling: the K Lines and Edges of Iron P. Palmeri (UMH-Belgium) T. Kallman (GSFC/NASA-USA) C. Mendoza & M. Bautista (IVIC-Venezuela) J. Krolik (JHU-USA)

  2. Plan • Introduction • Atomic Data • Photoionized Plasma Modeling • Conclusions

  3. Serlemitsos, et al, 1973 Introduction • Iron K lines are observed in (almost) all X-ray sources • First reported in rocket observations of the supernova remnant Cas A

  4. Tanaka et al., 1996 Introduction • Appear in a relatively unconfused region • Emitted efficiently over wide range of temperatures and ionization states • Relativistically broaden and red-shifted lines observed in galactic black hole candidates

  5. Introduction The world of X-ray observatory is changing: RXTE EXOSAT Compton ASCA XMM 1000 km/s Chandra 300 km/s Astro-E2

  6. Atomic Data • Motivation: they were scarce and not sufficiently accurate especially for the M-shell ions (Fe I-XVII) • Methods: standard atomic codes, i.e. AUTOSTRUCTURE (Badnell), HFR (Cowan) & BPRM (IP/RmaX Projects)

  7. Atomic Data • L-shell ions (Fe XVIII-XXV) CI: {2s,2p}N+[1s]{2s,2p} N+1+up to double excitations to M-shell Semi-empirical corrections: compilation of Shirai et al (2000) • M-shell ions (Fe I-XVII) Focus on K-vacancy states produced by removing a 1s electron from the ground configuration No experimental energies  Ab initio calculations Few experimental data (wavelengths): Fe X & solid state

  8. Core Relaxation Effects Electrons in K-vacancy & valence configurations see radically different potentials  different orbitals for initial & final states of inner-shell transitions  affects level energies, wavelengths & rates !!! -increase radiative rates by ~5-10% -increase KLL rates by ~10% -no systematic effect on KLM rates -decrease KMM rates by ~10%

  9. Damping Effect Resonances before K-edge Participator channels Spectator channels (Damping channels)

  10. Damping Effect: Photoabsorption With damping Without damping Fe XVII Fe XXIII

  11. Damping Effect: Electron Impact Without damping Fe XIX With damping 2p43P2 [1s]2p5 3Po2 [1s]2p5 3Po1 [1s]2p5 3Po0

  12. Line Energy vs. Ionization Stage Blue=Makishima Black=these studies Complicated K line structure Line moves to red near Fe IX

  13. Edge Energy vs. Ionization Stage Blue=Makishima Black=these studies In first row ions, ground level is split by various valence configurations In 2nd and 3rd row ions, Splitting is smaller, Results differ significantly From previous

  14. MCDF Jacobs- Rosznyai experiment HFR Auto-S Kaastra-Mewe K/K ratio vs. Ionization Stage  K/Kratio is a potential diagnostic of ionization

  15. Experiment Auto-S HFR Kaastra-Mewe Jacobs-Rosznyai Fluorescence Yield vs. Ion. Stage

  16. Photoionized Plasma Modeling With XSTAR • Photoionization of a gas by intense external X-ray source (dominant) • Other processes affecting ionization, excitation & temperature are in equilibrium • Local conditions (ionization fractions, temperature, opacity) parameterized by •  =Ionization parameter • =4Ionizing flux/gas density

  17. Photoionized Plasma Modeling: Atomic Processes • Each ion has ~3-30 K-vacancy levels which can be populated by photoionization • ~4-100 K lines per ion considered in our treatment

  18. temperature Ionization balance  =Ionization parameter=4Ionizing flux/gas density Ionization Balance & Temperature 104<T<108K

  19. Emissivity j~ n2 Line Emissivity vs. 

  20. Log =2 Line Emissivity vs. density

  21. Line Emissivity vs. density (continued) Log(n)=12 Log(n)=16

  22. Line Emissivity vs. Optical Depth Multiplier Lines can be suppressed by Auger destruction

  23. Emissivity averaged over constant density slab with log(x)=2 Line Emissivity vs. Column Density Shift of ionization from high to low will be detectable in reprocessed spectrum 1/N decrease marks the Breakdown of the optically thin approximation

  24. XMM Epic PN Astro-E XRS Assuming log()=2, log(N)=23, 100 mcrab source, tobs= 100 ksec Simulated Spectra

  25. Conclusions • Structure of Iron K shell is more complicated than has been previously appreciated, & care is needed to accurately compute useful quantities • There is a shortage of experimental data needed for accurate spectral modeling especially in intermediate & low ionization stages • Converging series of damped resonances act to smear absorption edges • Emission lines contain structure which has diagnostic value, even for low ionization gas

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