EBIT Observation of Low Charge State Ar Dielectronic Recombination Features Near the Unknown Faint X-Ray Feature Found in the Stacked Spectrum of Galaxy Clusters

Published

February 20, 2019

Author(s)

A. Gall, A. Foster, R. Silwal, Joan M. Dreiling, A. Borovik, E. Kilgore, M. Ajello, John Gillaspy, Yuri Ralchenko, Endre Takacs

Abstract

Motivated by possible atomic origins of the unidentified emission line detected at 3.55 keV - 3.57 keV in a stacked spectrum of galaxy clusters (Bulbul et al. 2014), an electron beam ion trap (EBIT) was used to investigate resonant dielectronic recombination (DR) processes in highly- charged Ar as a possible contributor to the emission feature. The He-like Ar DR induced transition 1s22l-1s2l3l' was suggested to produce a 3.62 keV photon (Bulbul et al. 2014) near the unidentified line at 3.57 keV and was the starting point of our investigation. Moderate and high resolution x-ray spectra, taken at multiple electron beam energies, were evaluated and interpreted with the aid of the collisional-radiative model NOMAD (Ralchenko & Maron 2001). Our spectra were then compared to spectra produced with AtomDB data and numerous Ar DR features from multiple ion charge-states in the energy region near the unidentified line were analyzed. We found that a number of features, primarily from Be-like Ar, are missing from AtomDB and may have implications in non-thermal plasma conditions.

Citation

Astrophysical Journal

Volume

872

Pub Type

Journals

Download Paper

https://iopscience.iop.org/article/10.3847/1538-4357/ab0177

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Keywords

Highly Charged Ions, x-ray spectroscopy, atomic processes, laboratory plasma

Citation

Gall, A. , Foster, A. , Silwal, R. , Dreiling, J. , Borovik, A. , Kilgore, E. , Ajello, M. , Gillaspy, J. , Ralchenko, Y. and Takacs, E. (2019), EBIT Observation of Low Charge State Ar Dielectronic Recombination Features Near the Unknown Faint X-Ray Feature Found in the Stacked Spectrum of Galaxy Clusters, Astrophysical Journal, [online], https://iopscience.iop.org/article/10.3847/1538-4357/ab0177, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=926572 (Accessed October 9, 2024)