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 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 64 674 Charge exchange induced X-ray emission of H and
He-like C-Si
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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
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Bytes Format Units Label Explanations
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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)
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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.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 01-Mar-2018