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Atomic Processes, Theory, and Data For X-Ray Plasmas

Atomic Processes, Theory, and Data For X-Ray Plasmas. Anil Pradhan, Sultana Nahar Guo-Xin Chen (ITAMP), Franck Delahaye Justin Oelgoetz, Hong Lin Zhang (LANL) (www.astronomy.ohio-state.edu/~pradhan) X-ray Diagnostics For Astrophysical Plasmas November 15-17, 2004 ITAMP, Harvard-Smithsonian

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Atomic Processes, Theory, and Data For X-Ray Plasmas

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  1. Atomic Processes, Theory, and DataFor X-Ray Plasmas Anil Pradhan, Sultana Nahar Guo-Xin Chen (ITAMP), Franck Delahaye Justin Oelgoetz, Hong Lin Zhang (LANL) (www.astronomy.ohio-state.edu/~pradhan) X-ray Diagnostics For Astrophysical Plasmas November 15-17, 2004 ITAMP, Harvard-Smithsonian Center For Astrophysics

  2. Atomic Processes, Theories, and Data • Processes: Particle Distributions in Lab and Astro Sources (Lab Astrophysics)  Resonances and Electron Distribution Functions in EBIT experiments • Theories: Electron Impact Excitation  Close Coupling vs. Distorted Wave • Data: Opacity Project and Iron Project  Excitation, Photoionization, Recombination, A-coefficients  X-ray Spectral Models • He-like ions in transient plasmas (e.g. X-Ray flares)  The Movie !

  3. Relativistic and Non-Relativistic R-matrix Codes For Atomic Processes Large-scale calculations with high precision and self-consistency

  4. Atomic Data For X-Ray Spectral Diagnostics • Laboratory Plasmas Sources: - Electron-Beam-Ion-Traps (EBIT) - Tokamaks - Magnetic Z-pinch and other ICF devices • Astrophysical Sources - Stellar Coronae - Active Galactic Nuclei - Supernova remnants • Are all these plasma sources the same ? • Are the line intensities and ratios the same ?

  5. Spectral Formation In Astro and Lab Sources • Particle Distribution: - Maxwellian  Most astrophysical cases - Non-Maxwellian  Tokamaks during heating phase (ECH, NBI, etc.), ‘runaway electrons’ in high-energy tail - Gaussian  EBIT (mono-energetic beam) - Bi-Maxwellian  Electron-ion storage rings • Radiation Field: - Stellar UV continuum  Blackbody Planck Function - Black Hole accretion  AGN, Non-thermal power-law L ~ E-a • Ionization Equilibrium or Non-Eqm: - Stationary - Transient (time-dependent)

  6. Benchmarking Laboratory and Astrophysical X-Ray Sources:Electron Impact Excitation (Chen etal., 2003) Ne- like

  7. Resonance and relativistic effects in prominent x-ray transitions

  8. Coupled Channel R-Matrix Theory vs. Distorted Wave Coupled Channel Distorted Wave • Includes only initial and final • channels in Eq. (1); no summation • Neglects channel coupling • Resonance states (intermediate • channels) NOT included in • wavefunction expansion • Limited number of resonances • may be considered in the • isolated resonance approximation • May not be adequate for highly • charged ions (weak transitions, • resonance effects) • Ab initio treatment of important atomic • processes with the same expansion: Eq.(1) • Electron impact excitation, radiative transitions, • and a self-consistent and unified treatment of • photoionization and (e + ion) recombination, • including radiative and dielectronic (RR+DR) Review: Nahar and Pradhan (2004) • Significant effects are included • Infinite series of resonances are considered

  9. Resonance Effects on the 3F/3C Line Ratio R-Matrix 3F Collision Strength Line Ratio vs. Te Filled Squares - DW Filled Circles – Distorted Wave

  10. Fe XVII 3F/3C Line Ratio vs. Temperature: Theory and Observations Beiersdorfer et.al., ApJ, 2004 Chen et.al. (JPB,36,453,2003) The measured 3F/3C value ~ 0.7 from tokamaks and EBIT agrees with theory

  11. Fe XVII Collision Strengths:Resonances up to n = 3 and n = 4 complexes Filled Poiints: Distorted Wave Blue: Gaussian Average Red: n =3 resonances

  12. Line Ratios and Electron Distribution Functions (EDF) in X-Ray Sources • All Fe XVII cross sections averaged over both EDFs – Maxwellian and Gaussian (Chen and Pradhan 2004) • Different sets of line ratios computed from collisional-radiative model including n = 4 levels • Solution to 3s/3d problem: • 3s/3d = (3F+3G+3H) / (3C+3D+3E) • Line ratios are source-specific • Tokamak, EBIT, and astrophysical measurements depend on EDFs • EBIT results are gaussian; for benchmarking need: • - Precise beam shapes • - Higher resolution (many more energies) • Oscillations due to distribution of resonances • Recombination-Cascades

  13. Fe XVII 3s/3d Ratio: Theory and ObservationsChen and Pradhan (2004) • Maxwellian average – solid line; Gaussian average – solid red line • Filled Blue – LLNL EBIT; Open Blue – NIST EBIT • Open red circles – Solar (T~ 4MK); Filled green – Capella (Chandra); • Open green – “ (XMM) • Extreme left – other measurements

  14. Unified electron-ion recombination (RR+DR): R-Matrix Theory and Experiments Maxwellian Averaged Rate Gaussian Averaged X-sections Expt Theory Expt Rates agree to < 20% Theory: Pradhan et.al. (ApJL, 549, L265, 2001) Expt: Savin et.al. (ApJS, 123, 687, 1999)

  15. R-Matrix Opacity/Iron/RmaX Project Data(Links From www.astronomy.ohio-state.edu/~pradhan) • Collisional Data For all Fe ions (also Fe-group) • Radiative Data Photoionization Cross Sections and Transition Probablities for most astrophysically abundant ions, including inner-shell photo-excitation, opacities etc. • New self-consistent photoionization and unified (RR+DR) electron-ion recombination cross sections and rates for over 50 ions (S. Nahar and collaborators), e.g. for X-ray applications - Li-, He-like: CIV/CV, OVI/OVII,…..,FeXXIV/FeXXV - Including total and level-specific recombination rate coefficients up to n<=10 - Unified recombination cross sections  DR spectrum • Electronic On-line Database: TIPTOPBASE and OPSERVER(C. Mendoza and collaborators)

  16. Code XRAD – Theoretical X-ray Absorption Spectrum • The Opacity Project and Iron Project Data (> 107 lines) • Ab initio data (theoretical energies, f-values, photoionization xsects, etc.) Fe L-shell opacity, ~ 1 keV features • Completeness of atomic data • General behavior and features • No detailed fitting

  17. XRAD Simulation of AGN MCG6-15-30 • Code XRAD uses ab initio • theoretical energies • No fitting of individual • features • Vary Te, Ne, Nz • Overall features obtained XRAD XSPEC OBS

  18. Code HELINE (Oelgoetz and Pradhan 2001,2004)Stationary and Transient Spectra of He-like Ions Time-Dependent Coupled Equations for Level Populations Collisional Ionization, Recombination, and Photoexcitation (thermal and non-thermal radiation fields) Collisional, Photoionized, and Hybrid Plasmas For Fe XXV the Helium “triplet” becomes a “quartet” with dielectronic satellites f,i,r z,x,y,w

  19. The 6.7 keV Ka complex of Fe XXVIonization Fractions of Iron In Different Plasma Sources Black Body Non-thermal Power-Law Coronal Eqm. Log Te

  20. Time-dependent Temperature, Radiation, and Ionization Fractions Electron Temperature Te(t) Example: X-Ray flare in accretion disc around a Black Hole Ionization Parameter U(t) = L / Ne Ionization Fractions coll. Ionization Te(t) + Photoionization U(t) ASTRO-E2 Hybrid: Te(t) & U(t) Time (Seconds)

  21. Time Evolution of Transient Plasmas Collisional (Lab) Photoionized Hybrid (Astrophysical) Dielectronic satellites dominate at early times in collisional case; very weak in photoionized case. Recombination dominates in all cases at late times t = 480 s t = 1080 s t = 1320 s t = 1560 s t = 1920 s Spectral Inversion z  w t = 2400 s Photon Energy (keV)

  22. Time-Dependent Photoionization and Collisional Ionization:The 6.7 KeV Ka Complex of He-like Fe XXV(Oelgoetz and Pradhan 2004)

  23. Time-Dependent Photoionization and Collisional Ionization:The 6.7 KeV Ka Complex of He-like Fe XXV(Oelgoetz and Pradhan 2004) PHOTOZN (U ~ 100) DOMINATES AT EARLY TIMES; DI-ELEC. SAT. (DES) q (1s2s2p) STRONG w q r t v,u y z

  24. Time-Dependent Photoionization and Collisional Ionization:The 6.7 KeV Ka Complex of He-like Fe XXV(Oelgoetz and Pradhan 2004) w IONIZN LAGS BEHIND RECOMBN; SMALL DES z y x j,r k

  25. Time-Dependent Photoionization and Collisional Ionization:The 6.7 KeV Ka Complex of He-like Fe XXV(Oelgoetz and Pradhan 2004) SPECTRAL INVERSION Z <--> W DURING RECOMBN PHASE AT LATE TIMES z x w y

  26. Conclusion • The Iron Project and the RmaX Project are providing large-scale atomic data of high accuracy using the R-matrix method for electron impact excitation, photoionization, unified electron-ion recombination, and transition probabilities in a self-consistent ab initio formulation • TIPTOPBASE  Electronic database • Spectral diagnostics and interpretation of plasma conditions my be source-specific • Electron distribution functions need to be known • Relativistic and resonance effects are crucial • Transient X-ray sources require new physical approximations, independent of global or local energy balance

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