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Spectral modeling of cosmic atomic plasmas Jelle S. Kaastra SRON
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Topics covered in this talk Fe XVII Collisional onisation & recombination rates Inner shell transitions Interstellar absorption 2
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Fe XVII The importance of accurate atomic data 3
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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! 4
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Resonance scattering & turbulence 5
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Resonance scattering (NGC 5813, de Plaa et al. 2012) 6
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Measured and predicted line ratios (de Plaa et al. 2012) 7
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Results NGC 5813: v turb = 140-540 km/s (15-45% of pressure) NGC 5044: v turb >320 km/s (> 40% turbulence) 8
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Fe XVII spectrum Capella (Bernitt et al. 2012) 9 15.01 Å 15.27 Å 16.78, 17.06, 17.10 Å
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3C/3D lines (Bernitt et al. 2012) 3C: 2p 6 1 S 0 – 2p 5 3d 1 P 1 (resonane) 3D: 2p 6 1 S 0 – 2p 5 3d 3 D 1 (forbidden) Forbidden line occurs due to mixing Excite Fe XVII using laser Allows to measure individual oscillator strengths 10
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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! 11
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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? 12
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Ionisation & recombination 13
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Ionisation balance Bryans et al. 2009 example: Fe @ 1 keV
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Bryans et al. in NEI work done with Makoto Sawada (T= 2 keV, compared to AR92) 15
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Larger differences for Ni (T = 2 keV) 16
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Recombining plasma (Fe; T=2 keV T = 0.6 keV) 17
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Non-thermal electrons (2 keV + 10% 20 keV) 18
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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 19
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Different versions of Cloudy the 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 20
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Differences photo-ionisation models 21
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Inner-shell transitions 22
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UTA = Unresolved Transition Array, blend of narrow features Due to inner-shell transitions Almost no accurate atomic data available before Sako et al. (2001) The Fe UTA 23
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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) 24
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Sample spectra RGS 600 ks, Detmers et al. 2011 (paper III) 25
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Example: AGN outflow Mrk 509 (Detmers et al. 2011) 26
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X-ray absorption Nasty correction factors are interesting! 27
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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 28
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Adding warm+hot gas, dust 29 Adding warm & hot gas Adding dust
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Oxygen complexity 30
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Interstellar dust SPEX (www.sron.nl/spex) currently has 51 molecules with fine structure near K- & L-edgeswww.sron.nl/spex Database still growing (literature, experiments; Costantini & De Vries) Example: near O-edge (Costantini et al. 2012) 31 22 Ang 23.7 Ang Transmission
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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)
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Are we detecting GEMS? 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 Mg silicate Metallic iron FeS Crystal olivine, pyroxene With Mg Glassy structure + FeS Cosmic rays+radiation Sulfur evaporation GEMS
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Final remarks We showed examples of different & challenging astrophysical modeling All depend on availability reliable atomic data The SPEX code (www.sron.nl/spex) allows to do this spectral modeling & fitting Code & its applications continuing development (since start 1972 by Mewe) 34
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