Spectral modeling of cosmic atomic plasmas
Jelle S. Kaastra
SRON
Topics covered in this talk
• Fe XVII
• Collisional onisation & recombination rates
• Inner shell transitions
• Interstellar absorption
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Fe XVII
The importance of accurate atomic data
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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!
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Resonance scattering & turbulence
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Resonance scattering(NGC 5813, de Plaa et al. 2012)
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Measured and predicted line ratios(de Plaa et al. 2012)
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Results
• NGC 5813:
vturb = 140-540 km/s (15-45% of pressure)
• NGC 5044:
vturb >320 km/s (> 40% turbulence)
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Fe XVII spectrum Capella(Bernitt et al. 2012)
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15.01 Å
15.27 Å
16.78,17.06,17.10 Å
3C/3D lines(Bernitt et al. 2012)
• 3C: 2p6 1S0 – 2p53d 1P1 (resonane)
• 3D: 2p6 1S0 – 2p53d 3D1 (forbidden)
• Forbidden line occurs due to mixing
• Excite Fe XVII using laser• Allows to measure
individual oscillator strengths
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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!
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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?
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Ionisation & recombination
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Ionisation balance Bryans et al. 2009
example: Fe @ 1 keV
Bryans et al. in NEIwork done with Makoto Sawada(T= 2 keV, compared to AR92)
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Larger differences for Ni(T = 2 keV)
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Recombining plasma(Fe; T=2 keV T = 0.6 keV)
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Non-thermal electrons(2 keV + 10% 20 keV)
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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
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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
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Differences photo-ionisation models
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Inner-shell transitions
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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
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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)
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Sample spectraRGS 600 ks, Detmers et al. 2011 (paper III)
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Example: AGN outflow Mrk 509 (Detmers et al. 2011)
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X-ray absorption
Nasty correction factors are interesting!
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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
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Adding warm+hot gas, dust
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Adding warm & hot gas
Adding dust
Oxygen complexity
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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)
3122 Ang 23.7 Ang
Tra
nsm
issi
on
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)
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, pyroxeneWith Mg
Glassy structure +FeS
Cosmic rays+radiation
Sulfur evaporation GEMS
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)
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