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Spectral modeling of cosmic atomic plasmas

This talk explores the importance of accurate atomic data in spectral modeling of cosmic atomic plasmas, focusing on Fe XVII, collisional ionization, recombination rates, inner-shell transitions, interstellar absorption, resonance scattering, turbulence, ionization and recombination balance, and the effects of dielectronic recombination updates.

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Spectral modeling of cosmic atomic plasmas

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  1. Spectral modeling of cosmic atomic plasmas Jelle S. Kaastra SRON

  2. Topics covered in this talk • Fe XVII • Collisional onisation & recombination rates • Inner shell transitions • Interstellar absorption

  3. Fe XVII The importance of accurate atomic data

  4. The importance of Fe XVII • Stable ion (Ne-like) • Coldest Fe ion emitting in Fe-L band (cool core clusters) • Has handful of strong lines  consistency checks • Strongest resonance line has large f resonance scattering effects useful diagnostic!

  5. Resonance scattering & turbulence

  6. Resonance scattering(NGC 5813, de Plaa et al. 2012)

  7. Measured and predicted line ratios(de Plaa et al. 2012)

  8. Results • NGC 5813: vturb = 140-540 km/s (15-45% of pressure) • NGC 5044: vturb >320 km/s (> 40% turbulence)

  9. Fe XVII spectrum Capella(Bernitt et al. 2012) 15.01 Å 16.78, 17.06, 17.10 Å 15.27 Å

  10. 3C/3D lines(Bernitt et al. 2012) • 3C: 2p61S0 – 2p53d 1P1 (resonane) • 3D: 2p61S0 – 2p53d 3D1 (forbidden) • Forbidden line occurs due to mixing • Excite Fe XVII using laser • Allows to measure individual oscillator strengths

  11. Resulting oscillator strength • Observed ratio of oscillator strengths 71% smaller than e.g. NIST value and others • If due to 3C line, than also in emission lower fluxes!

  12. Groups revisited • Implications Bernitt et al.: model X/3C 40% higher • Resonance scattering makes observed X/3C higher • Source like NGC 5044 would fall below line! • Should full effect be attributed to 3C alone? Or also to 3D?

  13. Ionisation & recombination

  14. Ionisation balance Bryans et al. 2009 example: Fe @ 1 keV

  15. Bryans et al. in NEIwork done with Makoto Sawada(T= 2 keV, compared to AR92)

  16. Larger differences for Ni(T = 2 keV)

  17. Recombining plasma(Fe; T=2 keV T = 0.6 keV)

  18. Non-thermal electrons(2 keV + 10% 20 keV)

  19. Effects of DR on photoionised plasmas • Kraemer et al. (2004): calculations for Fe with & without low-T DR • Compare to O ions: • Differences up to factor 2 • May explain “mismatch” in Seyfert galaxy fits

  20. Different versions of Cloudythe effects of dielectronic recombination updates • Chakravorty et al. 2008: • Same ionising continuum (Γ=1.8) • Differences in number & location stable branches • Due to updated DR rates

  21. Differences photo-ionisation models

  22. Inner-shell transitions

  23. The Fe UTA • UTA = UnresolvedTransition Array, blend of narrow features • Due to inner-shell transitions • Almost no accurate atomic data available before Sako et al. (2001)

  24. Calculations & Lab measurements of inner-shell transitions • Example: oxygen K-shell transitions (Gu et al. 2005) • Lab measurements: EBIT • Calculations: FAC •  accurate λ for O V 1s-2p main line: uncertainty only 3 mÅ (50 km/s)

  25. Sample spectraRGS 600 ks, Detmers et al. 2011 (paper III)

  26. Example: AGN outflow Mrk 509 (Detmers et al. 2011)

  27. X-rayabsorption Nasty correction factors are interesting!

  28. Interstellar X-ray absorption • High-quality RGS spectrum X-ray binary GS1826-238 (Pinto et al. 2010) • ISM modeled here with pure cold gas • Poor fit

  29. Adding warm+hot gas, dust Adding warm & hot gas Adding dust

  30. Oxygen complexity

  31. Interstellar dust • SPEX (www.sron.nl/spex) currently has 51 molecules with fine structure near K- & L-edges • Database still growing (literature, experiments; Costantini & De Vries) • Example: near O-edge (Costantini et al. 2012) Transmission 23.7 Ang 22 Ang

  32. Absorption edges: more on dust • optimal view O & Fe • Fe 90%, O 20% in dust (Mg-rich silicates rather than Fe-rich: Mg:Fe 2:1 in silicates) • Metallic iron + traces oxydes • Shown: 4U1820-30, (Costantini et al. 2012)

  33. Are we detecting GEMS? FeS GEMS= glass with embedded metal & sulphides (e.g. Bradley et al. 2004) interplanetary origin, but some have ISM origin  invoked as prototype of a classical silicate Crystal olivine, pyroxene With Mg Cosmic rays+radiation Metallic iron Mg silicate Glassy structure + FeS Sulfur evaporation GEMS

  34. Finalremarks • We showedexamplesof different & challengingastrophysicalmodeling • Alldepend on availability reliableatomic data • The SPEX code (www.sron.nl/spex) allowsto do thisspectralmodeling & fitting • Code & itsapplicationscontinuingdevelopment (since start 1972 byMewe)

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