THE FORMATION OF SH$^+$ VIA S$^{2+}$ + H$_2$ IN X-RAY DOMINATED REGIONS
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Date
2008
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Ohio State University
Abstract
A. Dalgarno first suggested thirty-two years ago that doubly-ionized $X^{2+}$ elements reacting with H$_2$ could lead to the formation of molecules in regions with a significant X-ray flux. However, few investigations of the effects of $X^{2+}$ on the formation of molecules have actually been conducted. Recent studies have found the reaction rate coefficients to be orders of magnitude higher than previously thought. This fact, combined with a renewed interest in the physics and chemistry of X-ray Dominated Regions (XDRs), points to a need to study the effects of $X^{2+}$ on molecule formation. We investigated how S$^{2+}$ + H$_2$ affects the formation of SH$^{+}$ for atomic gas exposed to an X-ray continuum typical of an Active Galactic Nucleus (AGN). As long as the fraction of S$^{2+}$ + H$_2$ reactions which lead to SH$^{+}$ formation exceeds a few percent, this process will be the dominant formation pathway for SH$^+$. This potentially has major consequences for our understanding of sulfur chemistry in galaxies where the energetics is dominated by AGN activity.
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Author Institution: Department of Physics, University of Cincinnati, Cincinnati, OH; Department of Physics \& Astronomy, University of Toledo, Toledo, OH; Department of Physics \& Astronomy and the Center for Simulation Physics, University of Georgia