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J/ApJ/844/7     X-ray line ratios for diverse ion collisions     (Mullen+, 2017)

Line ratios for solar wind charge exchange with comets. Mullen P.D., Cumbee R.S., Lyons D., Gu L., Kaastra J., Shelton R.L., Stancil P.C. <Astrophys. J., 844, 7 (2017)> =2017ApJ...844....7M
ADC_Keywords: Atomic physics ; X-ray sources Keywords: atomic data ; atomic processes ; comets: general ; line: formation ; X-rays: general Abstract: Charge exchange (CX) has emerged in X-ray emission modeling as a significant process that must be considered in many astrophysical environments- particularly comets. Comets host an interaction between solar wind ions and cometary neutrals to promote solar wind charge exchange (SWCX). X-ray observatories provide astronomers and astrophysicists with data for many X-ray emitting comets that are impossible to accurately model without reliable CX data. Here, we utilize a streamlined set of computer programs that incorporate the multi-channel Landau-Zener theory and a cascade model for X-ray emission to generate cross sections and X-ray line ratios for a variety of bare and non-bare ion single electron capture (SEC) collisions. Namely, we consider collisions between the solar wind constituent bare and H-like ions of C, N, O, Ne, Na, Mg, Al, and Si and the cometary neutrals H2O, CO, CO2, OH, and O. To exemplify the application of this data, we model the X-ray emission of Comet C/2000 WM1 (linear) using the CX package in SPEX and find excellent agreement with observations made with the XMM-Newton RGS detector. Our analyses show that the X-ray intensity is dominated by SWCX with H, while H2O plays a secondary role. This is the first time, to our knowledge, that CX cross sections have been implemented into a X-ray spectral fitting package to determine the H to H2O ratio in cometary atmospheres. The CX data sets are incorporated into the modeling packages SPEX and Kronos. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 64 674 Charge exchange induced X-ray emission of H and He-like C-Si
See also: J/A+A/376/1113 : Line ratios for helium-like ions (Porquet+, 2001) J/ApJS/167/315 : NaIX-X + MgX-XI recombination rate coefficients (Nahar+, 2006) J/A+A/526/A115 : Electron-impact excitation of H-like ions (Malespin+, 2011) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 7 F7.2 eV PhE [298.9/2646.5] Photon energy 9- 14 A6 --- Ion Ion designation 16- 18 A3 --- Target Target (CO, CO2, H2O, N2, O or OH) 20- 28 A9 --- Line Emission line 30- 35 F6.4 --- I200 [0/7.2] Normalized intensity at 200km/s collision velocity (1) 37- 43 F7.4 --- I400 [0/11.8] Normalized intensity at 400km/s collision velocity (1) 45- 50 F6.4 --- I600 [0/9.5] Normalized intensity at 600km/s collision velocity (1) 52- 57 F6.4 --- I800 [0/6.9] Normalized intensity at 800km/s collision velocity (1) 59- 64 F6.4 --- I1000 [0/5.7] Normalized intensity at 1000km/s collision velocity (1)
Note (1): Line Ratios for X-ray emission resulting from C-Si bare and H-like ions charge exchange (CX) collisions with N2, H2O, CO, CO2, OH, and O. Note that all lines are normalized to the Lyalpha line and Kalpha resonant line for bare ion and non-bare ion collisions, respectively. Line ratios for bare ion collisions were obtained by applying the low energy distribution (Equation 3.2) to multi-channel Landau-Zener (MCLZ) n-resolved cross sections. For non-bare ion collisions, MCLZ nlS-resolved cross sections were used to obtain these ratios. See text for details.
History: From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 01-Mar-2018
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