Abstract

The cold ISM and dust properties are key elements to understand the assembly and nature of the first QSOs and their massive host galaxies at the Reionization Epoch. I will present results on a sample of QSOs at 5 6 QSOs (Zappacosta+23), powered by the fastest growing and most massive Super Massive Black Holes (SMBH) at their epoch, and likely assembled from the largest black-hole (BH) seeds, or experienced peculiar, possibly supercritical, mass accretion histories. NOEMA and ALMA (sub) kpc-resolution observations allowed us to perform detailed study of the kinematics and dynamics of the gas in the host galaxies of our sample, revealing signatures of mergers, H2O disks, powerful outflows, and provided the first CO detections at z>7, and even the presence of the highest-z bulge candidate known to date. Moreover, the cold dust continuum measurements enabled us to obtain a reliable and accurate determination of the dust properties and a precise estimate for the star formation rate of the QSO ’s host galaxies, thanks to unprecedented ALMA observations at very high frequency (670 GHz, Band 9). I will also focus on the properties of some well studies quasars at Reionization (QSO J2310 +1855 at z_{6, QSO J0100 +2802 at z}6.3 and QSO J1007 +2115 at z~7.5), and discuss the evolutionary scenario of these objects and the role of feedback in determining their evolution, studying the evolutionary path of SMB Hs and their host galaxies.