Charge Exchange Spectra of Hydrogenic and He-like Iron Page: 3 of 25
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To be submitted to the Astrophysical Journal
Charge Exchange Spectra of Hydrogenic and He-like Iron
B. J. Wargelin', P. Beiersdorfer2, P. A. Neill3, R. E. Olson4, and J. H. Scofield2
We present H-like Fe XXVI and He-like Fe XXV charge-exchange spectra re-
sulting from collisions of highly charged iron with N2 gas at an energy of ~10
eV amu-- in an electron beam ion trap. Although high-n emission lines are not
resolved in our measurements, we observe that the most likely level for Fe25+ 4
Fe24+ electron capture is rima ~ 9, in line with expectations, while the most likely
value for Fe26+ - Fe25+ charge exchange is significantly higher. In the Fe XXV
spectrum, the Ka emission feature dominates, whether produced via charge ex-
change or collisional excitation. The Ka energy centroid is lower in the former
case than the latter (6666 versus 6685 eV, respectively), as expected because
of the strong enhancement of emission from the forbidden and intercombination
lines, relative to the resonance line, in charge-exchange spectra. In contrast,
the Fe XXVI high-n Lyman lines have a summed intensity greater than that of
Lya, and are substantially stronger than predicted from theoretical calculations
of charge exchange with atomic H. A discussion is presented of the relevance of
our results to studies of diffuse Fe emission in the Galactic Center and Galactic
Ridge, particularly with ASTR O-E2.
Subject headings: atomic data atomic processes X-rays: diffuse background
Smithsonian Astrophysical Observatory, Harvard-Smithsonian Center for Astrophysics, 60 Garden
Street, MS-70, Cambridge, MA 02138; email@example.com
2Department of Physics, Lawrence Livermore National Laboratory, Livermore, CA 94550
3Department of Physics, University of Nevada, Reno, NV 89557
4Department of Physics, University of Missouri, Rolla, MO 65401
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Wargelin, B J; Beiersdorfer, P; Neill, P A; Olson, R E & Scofield, J H. Charge Exchange Spectra of Hydrogenic and He-like Iron, article, April 27, 2005; Livermore, California. (https://digital.library.unt.edu/ark:/67531/metadc879558/m1/3/: accessed April 25, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.