Title:
Plasma code for astrophysical charge exchange emission at X-ray wavelengths
Authors:
Gu, Liyi; Kaastra, Jelle; Raassen, A. J. J.
Affiliation:
AA(SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA,
Utrecht, The Netherlands L.Gu@sron.nl), AB(SRON Netherlands Institute for
Space Research, Sorbonnelaan 2, 3584 CA, Utrecht, The Netherlands; Leiden
Observatory, Leiden University, PO Box 9513, 2300 RA, Leiden, The Netherlands),
AC(SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA,
Utrecht, The Netherlands; Astronomical Institute "Anton Pannekoek", University
of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands)
Publication:
Astronomy & Astrophysics, Volume 588, id.A52, 11 pp. (A&A Homepage)
Publication Date:
04/2016
Origin:
EDP Sciences
Astronomy Keywords:
atomic data, atomic processes, comets: individual: C/2000 WM1 (LINEAR)
DOI:
10.1051/0004-6361/201527615
Bibliographic Code:
2016A&A...588A..52G
Abstract
Charge exchange X-ray emission provides unique insight into the interactions
between cold and hot astrophysical plasmas. Besides its own profound science,
this emission is also technically crucial to all observations in the X-ray band, since
charge exchange with the solar wind often contributes a significant foreground
component that contaminates the signal of interest. By approximating the cross
sections resolved to n and l atomic subshells and carrying out complete radiative
cascade calculation, we have created a new spectral code to evaluate the charge
exchange emission in the X-ray band. Compared to collisional thermal emission,
charge exchange radiation exhibits enhanced lines from large-n shells to the
ground, as well as large forbidden-to-resonance ratios of triplet transitions. Our
new model successfully reproduces an observed high-quality spectrum of comet
C/2000 WM1 (LINEAR), which emits purely by charge exchange between solar wind ions and cometary neutrals. It demonstrates that a proper charge exchange
model will allow us to probe the ion properties remotely, including charge state,
dynamics, and composition, at the interface between the cold and hot plasmas.