Breaking the rules at z=0.45: the rebel case of RBS 1055

Very luminous quasars are unique sources for studying the circumnuclear environment around supermassive black holes. The current paradigm for Active Galactic Nuclei (AGN) postulates the presence of several components that contribute to the overall spectral shape in the X-rays. The hot (kTe =50-100 keV) and warm (kTe =0.1-1 keV) coronae are responsible for the hard and soft power law continua while the circumnuclear toroidal reflector accounts for the Iron Kα α emission line and the associated Compton hump. However, all these spectral features are simultaneously observed only in a handful of sources above z=0.1. We show results from a long NuSTAR observation (250 ks long) of the bright quasar RBS 1055 at z=0.45, performed on March 2021 and from archival XMM-Newton pointings (185 ks long) taken on July 2014. An optical spectrum of the source taken with the Double Spectrograph at the Palomar Observatory, quasi-simultaneous to the NuSTAR one, is also analyzed