NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-25 T13:41:04 PDT
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For refcode 2004MNRAS.353..468O:
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NED Abstract

Copyright by Royal Astronomical Society. 2004MNRAS.353..468O Excess ionization and soft X-ray emission from cooling flow clusters Oh, S. Peng Abstract. X-ray spectroscopy of cooling flow clusters reveal an unexpected deficit of soft X-ray emission lines from gas at ~1/3 of the ambient plasma temperature, across a wide range of X-ray luminosities and virial temperatures. We propose excess ionization from either a population of suprathermal electrons or photoionization by X-ray continuum emission from hot gas or a central active galactic nucleus as a means of decoupling the thermal state of the gas from its emission line spectrum. As they generally become important at some fixed fraction of the cluster gas temperature, such mechanisms could in principle explain both the universality and the temperature dependence of the emission line suppression, properties which none of the present-day models based on gas heating can explain. Ultimately these models cannot explain the observations; however, they have attractive and robust features which could be useful in elucidating a final solution to the soft X-ray deficit. Keywords: galaxies: clusters: general, cooling flows, X-rays: galaxies
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