Atomic data: state of the art and future perspectives

Jelle Kaastrawith Ton Raassen, Liyi Gu, Junjie Mao, Igone

Urdampilleta, Missagh Mehdipour

SRON & Leiden University

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Introduction

• X-ray emitting plasmas everywhere: – Solar system to cosmic web filaments

• Broad range environments & physical conditions:– collisional ionised, photo-ionised, transiently ionised

• High resolution X-ray spectroscopy key to understand these sources

• Next year launch ASTRO-H with SXS calorimeter• Old models not always most up to date atomic physics• Need tool to model these different sources with same,

consistent set atomic parameters

Spectroscopic codes @ SRON

• Short history:– 1972 Mewe– 1975 Mewe-Gronenschild– 1985 Mewe-Gronenschild-

Van den Oord– 1990 Meka– 1994 Mekal– 1992 SPEX

• 1992 Version 1• 2001 Version 2• 2015 Version 3 (expected release December)

• Evolution from plasma model to full astrophysical model including data analysis (fitting), plotting & diagnostic output

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Need for updates

• Example: Mewe code (still core present SPEX models) approximates radiative recombination contribution to lines by local power-law

• Okay for CIE but:• Large deviations for

recombining / ionising plasma

Tmax

log T

log

rate

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Requirements for updates

• Code must allow options for fast calculation yet accurate enough

• Minimise number of mathematical operations & data storage for the cross sections/rates

• follow original strategy of Mewe: simple, accurate & fast approximations, but more accurate & complete than before

• Restrict to Z ≤ 30 (astrophysically most relevant)

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Updates to atomic data

• For full model, need updates of many processes:– Collisional & photo-ionisation cross sections– Transition probabilities– Auto-ionisation rates– Recombination rates– Line energies– Etc.

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Comparison of codes(with Junjie Mao)

Wavelength (Å)

Wavelength (Å)

SPEX V 3.0βATOMDB V3.0.2

Log T (K) Fe

O

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Collisional ionisation(with Igone Urdampilleta)

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Motivation

• In the past, several compilations• Recent one: Dere 2007• Almost always give total ionisation rates• Subshells needed for inner-shell line emission• New data published since 2007• Revisit collisional ionisation rates

Collisional ionisation for atoms and ions of H to Zn

Direct ionization cross section fitting procedure:

Relativistic correction (Quarles 1976 and Tinschert et al. 1989):

Excitation Autoionization fit (Mewe 1972):

where, Ee electron energy I ionisation potential A, B, D, E fit parameters C Bethe constant R relativistic correction

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Examples of fits to collisional ionisation cross sections

QI2 (

10-2

4 m

2 keV

2 )

1s

2s

Note Dimensionless scaling

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QI2 (

10-2

4 m

2 keV

2 ) Relativistic correction

Note dimensionless scaling

I ~ Z2 for 1s shell H-sequence

-Cl-Ar-K-Ca-Sc-Ti-V

-Cr-Mn-Fe-Co-Ni-Cu-Zn

-Cl-Ar-K-Ca-Sc-Ti-V

-Cr-Mn-Fe-Co-Ni-Cu-Zn

-Cl-Ar-K-Ca-Sc-Ti-V

-Cr-Mn-Fe-Co-Ni-Cu-Zn

-Cl-Ar-K-Ca-Sc-Ti-V

-Cr-Mn-Fe-Co-Ni-Cu-Zn

-Cl-Ar-K-Ca-Sc-Ti-V-Cr-Mn-Fe-Co-Ni-Cu-Zn

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Radiative recombination(with Junjie Mao)

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Radiative recombination

• Need individual rates to different excited shells for calculation of line spectrum

• Also need cooling rate associated to the recombination (kinetic energy captured electron averaged over the recombination rate)

• Start with hydrogen-like systems

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RR Cross Section

PI Cross SectionStorey&Hummer (1991)

EXACT

AUTO STRUCTUREBadnell (2006)

FAC Gu (2003)

cf

Analytic

Free e- distribution

Milne relation

RR rates

Parameterisation

R(T) = a0 T-b0-c0logT (1+a2T-b2) / (1 + a1 T-b1)

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Fitting accuracy

• Vast majority: accurate within few %

• Very limited number outliers

• Usually unimportant transitions

• Example: C I n=5 1D2 level, still ~15% accuracy

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Photoionised plasmas(with Missagh Mehdipour)

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Obscuration in NGC 5548

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Differences photoionisation models(NGC 5548 obscured case)

Ξ = Fion / nkTc

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Total radiative recombination rates

• Seaton approximation: simple analytic form for low to intermediate T

• Fails at higher T• Previously widely used (e.g. Arnaud &

Rothenflug 1985 balance)

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Effects of update for photoionised plasmas

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He-like triplets and absorption(with Missagh Mehdipour)

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He-like R-ratio in Active Galactic Nuclei(Seyfert 2 galaxies)

Theory: Porquet & Dubau (2000)

Landt et al. 2015, observations

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1s22s1s2s(1S)2p 2P 1s22s1s2s(3S)2p 2P

w

z

x,y

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Line broadening

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Line broadening

• Thermal Doppler broadening

• Turbulent broadening• Natural broadening?• For Fe-K, FWHM 0.2-1.0

eV (e.g. Brown et al.)• Corresponds to 10-50

km/s• Need Voigt profiles

Thermal broadening only

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Charge transfer modelingsee talk this afternoon by Liyi Gu

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Conclusions

• Astrophysical sources sometimes found in remarkable areas of parameter space

• New X-ray missions like ASTRO-H (launch 2016) demand more detail & accuracy (but also Chandra & XMM-Newton benefit)

• Work in progress: update atomic parameters in X-ray spectral models to account for this

• SPEX ( www.sron.nl/spex ) Version 3 will contain these updates (release late 2015)