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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