The HELLAS2XMM survey: XI. Unveiling the nature of X-ray bright optically normal galaxies - Civano, F.; Mignoli, M.; Comastri, A.; Vignali, C.; Fiore, F.; Pozzetti, L.; Brusa, M.; La Franca, F.; Matt, G.; Puccetti, S.; Cocchia, F. (Astronomy and astrophysics (Berlin), 2007)
Keywords: Astronomy; Earth, ocean, space; Exact sciences and technology; Red shift; Hard x radiation; X-ray galaxies; X-rays: galaxies; Cosmic x-ray sources; Active galaxies; Point sources; Solid angle; Light emission; Extended source; galaxies: active; Surface brightness; Emission line; X ray emission