Marchese, E.E.MarcheseDELLA CECA, RobertoRobertoDELLA CECACACCIANIGA, AlessandroAlessandroCACCIANIGASEVERGNINI, PaolaPaolaSEVERGNINICorral, A.A.CorralFanali, R.R.Fanali2024-01-302024-01-3020120004-6361http://hdl.handle.net/20.500.12386/34665Context. Active galactic nuclei (AGN) emit radiation over a wide range of wavelengths, with a peak of emission in the far-UV region of the electromagnetic spectrum, a spectral region that is historically difficult to observe. Aims: Using optical, GALEX UV, and XMM-Newton data we derive the spectral energy distribution (SED) from the optical/UV to X-ray regime of a sizeable sample of AGN. The principal motivation is to investigate the relationship between the optical/UV emission and the X-ray emission and provide bolometric corrections to the hard X-ray (2-10 keV) energy range, kbol, the latter being a fundamental parameter in current physical cosmology. Methods: We construct and study the X-ray to optical SED of a sample of 195 X-ray selected Type 1 AGN belonging to the XMM-Newton bright serendipitous survey (XBS). The optical-UV luminosity was computed using data from the Sloan Digital Sky Survey (SDSS), from our own dedicated optical spectroscopy and the satellite GALaxy evolution EXplorer (GALEX), while the X-ray luminosity was computed using XMM-Newton data. Because it covers a wide range of redshift (0.03 < z ≲ 2.2), X-ray luminosities (41.8 < log L[2-10] keV < 45.5 erg/s) and because it is composed of "bright objects", this sample is ideal for this kind of investigation. Results: We confirm a highly significant correlation between the accretion disc luminosity Ldisc and the hard X-ray luminosity L[2-10] keV, in the form Ldisc ∝ Lβ[2-10] keV, where β = 1.18 ± 0.05. We find a very shallow dependence of kbol on the X-ray luminosity with respect to the broad distribution of values of kbol. We find a correlation between kbol and the hard X-ray photon index Γ2-10 keV and a tight correlation between the optical-to-X-ray spectral index αox and kbol, so we conclude that both Γ2-10 keV and αox can be used as a proxy for kbol.STAMPAenArticle10.1051/0004-6361/2011175622-s2.0-84857422729http://arxiv.org/abs/1111.4409v2https://www.aanda.org/articles/aa/full_html/2012/03/aa17562-11/aa17562-11.html2012A&A...539A..48MFIS/05 - ASTRONOMIA E ASTROFISICA