X-ray spectroscopy in the microcalorimeter era I: Effects of Fe XXIV Resonance Auger Destruction on Fe XXV K$\alpha$ spectra

Abstract

We discuss the importance of Fe${}^{23+}$ in determining the line intensities of the Fe XXV K$\alpha$ complex in an optically thick cloud, and investigate the prediction of Liedahl (2005) on Resonance Auger Destruction (RAD) with CLOUDY. Although initially motivated by the Perseus cluster, our calculations are extended to the wide range of column densities encountered in astronomy. A Fe XXV line photon can change/lose its identity upon absorption by three-electron iron as a result of "line interlocking". This may lead to the autoionization of the absorbing ion, ultimately destroying the Fe XXV K$\alpha$ photon by RAD. Out of the four members in the Fe XXV K$\alpha$ complex, a significant fraction of the x line photons is absorbed by Fe${}^{23+}$ and destroyed, causing the x line intensity to decrease. For example, at a hydrogen column density of 10${}^{25}$ cm${}^{-2}$, $\sim$ 32\% of x photons are destroyed due to RAD while w is mostly unaffected. The line intensity of y is slightly ($\le$2\%) reduced. z is not directly affected by RAD, but the contrasting behavior between z and x line intensities points towards the possible conversion of a tiny fraction ($\sim$ 2\%) of x photons into z photons. The change in line intensities due to Electron Scattering Escape (ESE) off fast thermal electrons is also discussed.

References in corpus (4)

• The Quiescent Intracluster Medium in the Core of the Perseus Cluster
• CHIANTI - an atomic database for emission lines - Paper XV: Version 9, improvements for the X-ray satellite lines
• X-ray spectroscopy in the microcalorimeter era II: A new Diagnostic on Column Density from the Case A to B Transition in H- and He-like Iron
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Cited by in corpus (4)

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• Cloudy in the microcalorimeter era: improved energies for Si and S K$\alpha$ fluorescence lines
• Spectroscopic modelling of two high-mass X-ray binaries, Cyg X--3 and 4U 1538--522