The softest X-ray sources in the ROSAT pointed catalog: WGACAT

Singh, K. P. ; Barrett, P. ; White, N. E. ; Giommi, P. ; Angelini, L. (1995) The softest X-ray sources in the ROSAT pointed catalog: WGACAT The Astrophysical Journal, 455 . pp. 456-467. ISSN 0004-637X

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We present a selection of X-ray sources with the softest observed spectral characteristics and discuss their nature. These "ultrasoft" sources were detected in 3 years of pointings with the ROSA T. These sources are predominantly found to be white dwarfs, magnetic cataclysmic variables, nearby late-type stars, and very X-ray soft active galactic nuclei. The broadband colors of the unidentified ultrasoft sources suggest that a number of them may have at least two components in their spectrum, as for example, is found in most cataclysmic variables. Some of these objects may represent the extreme of their respective populations, for example, unusual galaxies, "supersoft" sources with steep low-energy spectrum and high X-ray luminosity (~1038 ergs s−1), active galactic nuclei, stars, etc. Follow-up studies in the optical and other wavebands are needed.

Item Type:Article
Source:Copyright of this article belongs to American Astronomical Society.
Keywords:Galaxies: Active; Stars: Novae; Cataclysmic Variables; Stars: White Dwarfs; X-rays: Stars
ID Code:59022
Deposited On:03 Sep 2011 12:10
Last Modified:18 May 2016 09:44

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