Paper

X-HESS: a large sample of highly accreting serendipitous AGN under the XMM-Newton microscope

Vagnetti, F, Tombesi, F, Laurenti, M, Middei, R, Piconcelli, E, Guainazzi, M

2023

Overview

The bulk of X-ray spectroscopic studies of active galactic nuclei (AGN) are focused on local (\\(z < 0.1\\)) sources with low-to-moderate (\\(< 0.3\\)) Eddington ratio (\\(_Edd\\)). It is then mandatory to overcome this limitation and improve our understanding of highly accreting AGN. In this work we present the preliminary results from the analysis of a sample of \\(70\\) high-\\(_Edd\\) radio-quiet AGN at \\(0.06 z 3.3\\), based on the 10th release of the XMM-Newton serendipitous source catalogue, that we named as XMM-Newton High-Eddington Serendipitous AGN Sample (X-HESS). Almost \\(35\\%\\) of the X-HESS AGN have multi-epoch archival observations and \\(70\\%\\) of the sources can rely on simultaneous OM optical data. First results reveal sources showing signatures of ultra-fast outflows and remarkable long- and short-term X-ray flux variations. Indeed in J095847.88+690532.7 (\\(z 1.3\\)), one of the most densely monitored objects hosting a$\\sim$ $10^9\\,M_\\odot\\( supermassive black hole, we discovered a variation of the soft X-ray flux by a factor of > 2 over approximately one week (rest-frame). Large variations in the power-law continuum photon index \\)\\Gamma\\( are also observed, questioning expectations from previously reported \\)\\Gamma - \\lambda_\\mathrm{Edd}\\( relations, for which \\)\\Gamma \\geq 2\\( would be a ubiquitous hallmark of AGN with \\)\\lambda_\\mathrm{Edd} \\sim 1$ .

• Publisher: Cornell University Library, arXiv.org
• Subject: Active galactic nuclei / Deposition / Serendipity / Soft x rays / Supermassive black holes / X-ray astronomy / XMM (spacecraft)