A Proposal For Improved Iron Project Collision Strengths

1. A Proposal For Improved Iron Project Collision Strengths Anil Pradhan Iron Project/ITAMP Workshop on High Accuracy Atomic Physics in Astronomy Aug. 7-9, 2006 Harvard-Smithsonian Center For Astrophysics

2. Coupled Channel R-Matrix Theory vs. Distorted Wave Coupled Channel Theory Distorted Wave Theory • 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 • 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

3. Fe II Emission From Accretion Disk Near Black Hole (Zhang etal 2006) Doppler Double-Peaked Broad Line Region AGN Models by Sigut and Pradhan (1998,2003), using IP data from the OSU group computed by H. Zhang, M. Bautista, S. Nahar etal., do NOT fit all spectra; accretion disk models favored! Hb [OIII] Fe II 2500 5600 Wavelength Sloan Quasar SDSS J2125-0813

4. Close Coupling Calculations for Fe II and Ni II • The most important and complex atomic systems in astrophysics • Fe II observed from nearly every class of astronomical object, from stars to black hole environments in centers of galaxies • Well over 100 terms, with fine structure levels, of astrophysical interest • Close coupling calculations in progress since the 70’s • Open 3d-shell  require multiple-electron excitations for outer-shell correlation, up to 4d, 5d configurations from 3d AND 3p • RMATRIX II enables ‘complete’ configurations

5. Term diagram for Fe II: Overlapping Target Configurations Strong CI precludes omission of any terms from low-lying configurations

6. The RMATRIX II APPROACH(P.G. Burke, V.M. Burke, C.J. Noble) • Enable large CI expansions, with ‘complete’ sets of allowed configurations • Efficient algorithms for algebraic manipulation of multiple-electron excitations in both - N-electron target configurations - (N+1)-electron correlation “ • Parallelized codes

7. Sets of N-electron Target Terms, (N+1)-electron Correlation Functions

8. Comparison of complete sets of the ‘4d5s’ (A3) and the ‘4d5s5d’ configurations (D3) C. Ramsbottom etal

9. Convergence of CI Expansions:Comparison of ‘4d5s5d’ (D3) and ‘4d5d’ (E2) configurations

10. Ni II Target Configurations(Oelgoetz and Pradhan, in progress)

11. First Few Target Energy Terms of Ni II(Over 100 considered)

12. Partial Ni II Collision Strengths (RM II codes not yet fully operational at OSC)

13. Benchmarking Laboratory and Astrophysical X-Ray Sources:Electron Impact Excitation Ne- like

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

15. 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

16. Proposed (Re-) Calculations of Collision Strengths • ~1000-level calculation for FeII, with (i) new BPRM codes (Eissner and Chen), (ii) parallel version (Ballance etal), (iii) RM II codes (Burke etal) • Similarly for Ni II • Converged collision strengths approaching ionization threshold(s) for FeXVII • Other heavy elements ?