J/ApJ/852/7 Theoretical charge exchange X-ray cross sections (Cumbee+, 2018)
Charge exchange X-ray emission due to highly charged ion collisions with H, He,
and H2: line ratios for heliospheric and interstellar applications.
Cumbee R.S., Mullen P.D., Lyons D., Shelton R.L., Fogle M., Schultz D.R.,
Stancil P.C.
<Astrophys. J., 852, 7 (2018)>
=2018ApJ...852....7C 2018ApJ...852....7C
ADC_Keywords: Atomic physics; X-ray sources
Keywords: atomic processes ; ISM: supernova remnants ; line: formation ;
Sun: heliosphere ; X-rays: general
Abstract:
The fundamental collisional process of charge exchange (CX) has been
established as a primary source of X-ray emission from the
heliosphere, planetary exospheres, and supernova remnants. In this
process, X-ray emission results from the capture of an electron by a
highly charged ion from a neutral atom or molecule, to form a highly
excited, high-charge state ion. As the captured electron cascades down
to the lowest energy level, photons are emitted, including X-rays. To
provide reliable CX-induced X-ray spectral models to realistically
simulate these environments, line ratios and spectra are computed
using theoretical CX cross sections obtained with the multi-channel
Landau-Zener (MCLZ), atomic-orbital close-coupling (AOCC),
molecular-orbital close-coupling (MOCC), and classical trajectory
Monte Carlo methods for various collisional velocities relevant to
astrophysics. X-ray spectra were computed for collisions of bare and
H-like C to Al ions with H, He, and H2 with results compared to
available experimental data. Using these line ratios, XSPEC models of
CX emission in the northeast rim of the Cygnus Loop supernova remnant
and the heliosphere are shown as examples with ion velocity
dependence.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 93 91 *Charge exchange X-ray emission with H targets
for single-electron capture (SEC)
table3.dat 93 74 *Charge exchange X-ray emission with He targets for SEC
table4.dat 93 91 *Charge exchange X-Ray emission with H2 targets
for SEC
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Note on table2.dat: Relative Line intensities are shown for all ions considered
in this work colliding with H. For this table, quantum-mechanical
molecular-orbital close-coupling (QMOCC) cross sections
are used when available for C5++H (Nolte+ 2012JPhB...45x5202N 2012JPhB...45x5202N),
N6++H (Wu+ 2011PhRvA..84b2711W 2011PhRvA..84b2711W), and O7++H (Jeff Nolte,
Private communication). AOCC cross-sections are then used for
Ne10++H for energies above 1keV/u. For C6++H and O8++H,
recommended cross-sections from Janev+ (1993ADNDT..55..201J 1993ADNDT..55..201J) are used,
and for N7++H (Harel+ 1998ADNDT..68..279H 1998ADNDT..68..279H), MOCC cross-sections are
used. In all other cases, and when energies are missing for the more
accurate methods, below 1keV/u, MCLZ low-energy l-distribution cross
sections are used, and for energies at and above 1keV/u, MCLZ
statistical l-distribution cross-sections are used.
Note on table3.dat: Same as Table 2, but for collisions with He.
Atomic-orbital close-coupling (AOCC) cross-sections are used for
C6++He (Frisch & Lin 1991PhR...202....1F 1991PhR...202....1F) for most energies, but
this table is primarily composed of MCLZ calculations.
Note on table4.dat: Same as Table 2, but for collisions with H2.
This table is composed entirely of multi-channel Landau-Zener (MCLZ)
calculations (Janev & Winter 1985PhR...117..265J 1985PhR...117..265J).
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See also:
J/ApJ/844/7 : X-ray line ratios for diverse ion collisions (Mullen+, 2017)
J/MNRAS/449/3323 : (Li-He)+ collisions non-radiative processes (Belyaev+,
2015)
J/A+A/376/1113 : Line ratios for helium-like ions (Porquet+, 2001)
Byte-by-byte Description of file: table[234].dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- Line Line designation
20- 29 F10.5 eV Energy [127.1/2640.2] Photon energy
31- 37 F7.5 195.7km/s 200ev/u [0/4.6] Collision velocity of 200eV.u-1
39- 45 F7.5 239.7km/s 300ev/u [0/4] Collision velocity of 300eV.u-1
47- 53 F7.5 309.4km/s 500ev/u [0.0002/3.5] Collision velocity
of 500eV.u-1
55- 61 F7.5 366.1km/s 700ev/u [0/3.2] Collision velocity of 700eV.u-1
63- 69 F7.5 437.5km/s 1000ev/u [0/3] Collision velocity of 1000eV.u-1
71- 77 F7.5 618.8km/s 2000ev/u [0/2.7] Collision velocity of 2000eV.u-1
79- 85 F7.5 757.8km/s 3000ev/u [0/2.7] Collision velocity of 3000eV.u-1
87- 93 F7.5 978.4km/s 5000ev/u [0/2.7] Collision velocity of 5000eV.u-1
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 19-Jul-2018