Speaker
Description
The Eddington ratio $\lambda_\mathrm{Edd}$\, is the key parameter that describes the accretion mode of active galactic nuclei (AGN). Among the different modes, high-$\lambda_\mathrm{Edd}\,$ accretion is particularly fascinating because of its implications in the context of accretion physics, as well as AGN feedback. However, due to their relative paucity in the local Universe (z$<$0.1), only a limited number of AGN accreting in the high-$\lambda_\mathrm{Edd}\,$ regime can benefit of currently available dedicated observations, especially at higher $z$. To tackle this issue we exploit the vast database of XMM-Newton serendipitous observations to create a new, large sample of highly accreting AGN named as XMM-Newton High-Eddington Serendipitous AGN Sample (X-HESS).
X-HESS includes 143 observations of 61 AGN, $\sim$40% of which disposing of multi-epoch observations, disclosing the unprecedented possibility to study not only the spectral but also variability features of high-$\lambda_\mathrm{Edd}\,$ AGN in much broader intervals of redshift, black hole mass, bolometric luminosity and $\lambda_\mathrm{Edd}\,$ with respect to the bulk of pre-existing AGN samples. Approximately two-thirds of the X-HESS observations are complemented with simultaneous OM measurements.
Thanks to the high-quality XMM-Newton observations we probe a large variety of correlations between the X-ray spectral, variability, optical/UV and physical properties of high-$\lambda_\mathrm{Edd}\,$ AGN, extending the dynamical range of previously reported relations towards poorly explored intervals.
