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The Discovery of Quasisoft and Supersoft Sources in External Galaxies

R. Di Stefano·A. K. H. Kong
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Abstract

We apply a uniform procedure to select very soft sources from point sources observed by Chandra in 4 galaxies. This sample includes one elliptical galaxy (NGC 4967), 2 face-on spirals (M101 and M83), and an interacting galaxy (M51). We have found very soft X-ray sources (VSSs) in every galaxy. Some of these fit the criteria for canonical supersoft sources (SSSs), while others are somewhat harder. These latter have characteristic values of kT < 300 eV; we refer to them as quasisoft sources (QSSs). We found a combined total of 149 VSSs in the 4 galaxies we considered; 77 were SSSs and 72 were QSSs. (See the paper for the original long abstract)

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R. Di Stefano, A. K. H. Kong. 2004-03-29. The Discovery of Quasisoft and Supersoft Sources in External Galaxies. https://doi.org/10.1086/421318

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