The X-rays Strike Back: unlocking the formation of SMBHs in quasars at early cosmic times

The rapid formation of SMBHs with masses >10^9M _sun, powering luminous quasars (QSOs) at the Epoch of Reionization (z=6-7.5) is one of the main open questions about the early (< 1 Gyr) Universe. Shedding light on their nuclear properties is crucial and therefore we tackled this challenge using our ~700 hours XMM-Newton Heritage program on the HYPERION sample of 18 luminous QSOs at z>6 powered by SMBH which experienced the fastest SMBH growth during their assembly. Our systematic investigation of these unprecedented-quality X-ray spectra revealed steeper X-ray spectral slopes compared to similar QSOs at z<6. In this talk we present the discovery of a highly-significant (>3 sigma) correlation between the X-ray continuum slope and the velocity of ionized disk winds. This relation, never reported before in AGN samples, unveils a connection between the properties of the inflowing and outflowing gas in the innermost part of the accretion disk, likely triggered by changes in its physical and geometrical properties. Then, we report a dependence of the X-ray continuum slope on the SMBH growth rate experienced by the SMBHs powering them. We discuss the implications of our results for the origin and evolution of first luminous QSOs and their SMBHs. Our findings, after 3 years of the HYPERION XMM-Newton Heritage program, stress the importance of investigating AGNs at early cosmic epochs on a sub-parsec scale in the X-rays to understand their formation, evolution and feedback processes.