Abstract

Observations of z>6 luminous quasars in the FIR regime probe the first steps of the galaxy-SMBH coevolution in the first billion years of the Universe. ALMA /NOEMA studies of luminous z>6 quasars accreting at nearly Eddington rate have shown that they are hosted by massive, highly star-forming galaxies, in agreement with theoretical predictions. However, early studies did not have either the resolution to study the resolved ISM of the host galaxies, nor the multi-frequency information to probe its properties, which is necessary to understand how the rapid growth of the central SMBH . I will present hyper-resolution (_{100-300 pc,} 0.”02-0.”04) ALMA observations of z=6.6-6.9 quasar host galaxies in the [CII] line. These observations reveal surprisingly compact host morphologies both in dust and [CII] emission (0.5-2 kpc), with a substantial fraction (~30%) of their intense star-forming activity and high gas mass concentrated within the inner 200-300 parsecs. The galaxies resolved kinematics come in a wide variety ranging from smooth rotating disks to dispersion-dominated systems and mergers. I will also show recent multi-frequency observations in specific systems, which probe the mechanisms behind the ionisation and temperature state of their ISM . Overall, these new observations showcase the potential of ALMA /NOEMA to study simultaneously the first massive galaxies in the Epoch of Reionisation and their co-evolution with their central SMBH .