The X-ray properties of the most luminous quasars with strong emission-line outflows

This research has utilised data obtained from the 4XMM XMM-Newton serendipitous stacked source catalogue 4XMM-DR14, compiled by the institutes of the XMM-Newton Survey Science Centre selected by ESA. The authors are grateful to the anonymous referee for useful and constructive comments. We thank the Munich Institute for Astro-, Particle, and BioPhysics (MIAPbP), which is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy - EXC-2094 - 390783311, for providing space for fruitful discussions on this work. AS is supported by the national doctoral scholarship from the Agencia Nacional de Investigacion y Desarrollo (ANID), folio de postulacion 21221788. AS personally acknowledges Olesya and Kirill Kuchay for their unwavering support. BT acknowledges support by the European Union's HE ERC Starting Grant No. 101040227 - WINGS. Views and opinions expressed are, however, those of the authors only and do not necessarily reflect those of the European Union or the European Research Council Executive Agency. Neither the European Union nor the granting authority can be held responsible for them. MJT acknowledges funding from the UKRI grant ST/X001075/1. ALR acknowledges funding from a Leverhulme Early Career Fellowship. We gratefully acknowledge funding from ANID - Millennium Science Initiative - AIM23-0001 and ICN12_009 (FEB), CATA-BASAL - FB210003 (FEB), and FONDECYT Regular - 1241005 (FEB). Support for this work was also provided in part by the National Aeronautics and Space Administration through Chandra Award Numbers GO4-25074X and AR1-22010X issued by the Chandra X-ray Centre, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics and Space Administration under contract NAS8-03060 and upon work supported by NASA under award 80NSSC24K0719.