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Liyi Gu (SRON) CHANDRA WORKSHOP 2015, CFA T. Raassen (SRON), J. Kaastra (SRON, Leiden) 1.X-ray from ion-neutral collision 2.Velocity-dependent cross section 3.Real data fitting: comet X-ray
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Over Barrierv, qσ tot Resonancev, q, Nσ tot, n, l Rotation mixv, ql Z q+ + A Z* (q-1)+ (n,l,S) + A + Emission by radiative cascade
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SWCX in comets geocoronal & heliospheric space Polar region of Jupiter North Polar Spur Wolf-Rayet stellar winds Supernova shock rims Starburst galaxies Cool core clusters
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Single electron capture with atomic hydrogen target (corrected for helium) Assumptions Take all available cross section data σ(v, n, l, s) from literatures & databases Challenge: incompleteness esp. for n, l-population Derive the “scaling-law” v-dependent n and l distributions, apply to the missing ions Method
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Resonance peak Velocity-dependent scaling law
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n < n p n > n p Rotation of internuclear axis determines l peak l population evolves with v, n A new v, n(q)- dependent scheme + five basic weighting function
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Triplet-to-Singlet Ratio (C5+ with H) Higher order processes (e.g., electron-electron interaction) Calculated in very few cases Significantly affect the G-ratio at ~500 km/s G-ratio Velocity (km/s) Nolte+2012 Black: s-resolved Red: statistical weight
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Highly excited p state to ground state transition (e.g., strong He-δ line) No up-excitation: 2 3 S 1 -2 3 P 0,1,2 > 1 1 S 0 -2 3 P 1,2 (forbidden line) CX model : lines from radiative cascade up to n=16 Bodewits (2007)
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OVIII Lyα OVIII Ly OVII He OVII Heα f i r NVII Lyα NVII Ly CVI Lyγ CVI Lyβ β γ δ ε β γ δ β γ δ f i r NeIX Heα NeX Lyα SiXII 5->2 SiXII 6 & 5->2 SiXII 6->2 Wavelength (Angstrom) 0.3 keV 500 km/s l-shell not fully implemented
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CX fitting: 0.14 keV 290 km/s C/2000 WM1, XMM-RGS Slow wind: 0.12-0.14 keV ACE record: 280-350 km/s
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Charge exchange creates forbidden-dominated and high shell-transition (e.g., He-δ, Ly-δ) spectra SPEX “CX” model: Velocity-, subshell- dependent cross sections Cascade complete up to n=16 Applicable to many objects for measuring ion composition, ionization temperature, even collision velocity CHANDRA WORKSHOP 2015, CFA
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