The HELLAS2XMM 1dF survey: on the nature of high X-ray to optical flux ratio sources

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dc.creatorFiore, F.
dc.creatorBrusa, M.
dc.creatorCocchia, F.
dc.creatorBaldi, A.
dc.creatorCarangelo, N.
dc.creatorCiliegi, P.
dc.creatorComastri, A.
dc.creatorLa Franca, F.
dc.creatorMaiolino, R.
dc.creatorMatt, G.
dc.creatorMolendi, S.
dc.creatorMignoli, M.
dc.creatorPerola, G. C.
dc.creatorSevergnini, P.
dc.creatorVignali, C.
dc.date2003-10-10
dc.date.accessioned2026-07-07T02:10:19Z
dc.date.available2026-07-07T02:10:19Z
dc.descriptionWe present results from the photometric and spectroscopic identification of 122 X-ray sources discovered by XMM-Newton in the 2-10 keV band (the HELLAS2XMM 1dF sample). One of the most interesting results (which is found also in deeper sourveys) is that ~20% of the sources have an X-ray to optical flux ratio (X/O) ten times or more higher than that of optically selected AGN. Unlike the faint sources found in the ultra-deep Chandra and XMM-Newton surveys, which reach X-ray (and optical) fluxes >~10 times lower than in the HELLAS2XMM sample, many of the extreme X/O sources in our sample have R~25 and are therefore accessible to optical spectroscopy. We report the identification of 13 sources with extreme X/O values. While four of these sources are broad line QSO, eight of them are narrow line QSO, seemingly the extension to very high luminosity of the type 2 Seyfert galaxies.
dc.descriptionTo appear in Proceeding of the "Multi-Wavelength Cosmology" Conference held in Mykonos, Greece, June 2003, ed.M. Plionis (Kluwer)
dc.identifierhttps://arxiv.org/abs/astro-ph/0310298
dc.identifierhttp://arxiv.org/abs/astro-ph/0310298
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/6702
dc.subjectAstrophysics
dc.titleThe HELLAS2XMM 1dF survey: on the nature of high X-ray to optical flux ratio sources
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