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The interaction between radio jets and quasar host galaxies plays a paramount role in quasar and galaxy co-evolution. However, very little is known at present about this interaction at very high−z. Here, we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations in Bands 7 and 3 of six radio-loud (RL) quasar host galaxies atz > 5. We recovered [C II] 158 μm line and underlying dust continuum emission at > 2σfor five sources, while we obtained upper limits for the CO(6-5) emission line and continuum for the remaining source. At the spatial resolution of our observations (∼1″​​_.0–1″​​_.4), we did not recover any perturbed or extended morphologies or kinematics, which are known signatures of potential mergers. These galaxies already host large quantities of gas (∼10¹⁰M_⊙), with [C II] luminosities ofL_[C II] ∼ 10^8 − 9 L_⊙and [C II]-based star formation rates of 30 − 400 M_⊙yr⁻¹. In building their radio/submillimeter (radio/submm) spectral energy distributions (SEDs), we found that in at least four cases, the 1 mm continuum intensity arises from a combination of synchrotron and dust emission. The initial estimation of synchrotron contribution at 300 GHz in these cases is of ≳10%. Assuming a scenario where the continuum emission is solely due to cold dust as an upper limit, we obtained infrared (IR) luminosities ofL_IR ∼ 10^{11 − 12} L_⊙. We compared the properties of the sources inspected here with a large collection of radio-quiet sources from the literature, as well as a sample of RL quasars from previous studies at comparable redshifts. We recovered a mild potential decrease inL_[C II]for the RL sources, which might be due to a suppression of the cool gas emission due to the radio jets. We did not find any [C II] emitting companion galaxy candidate around the five RL quasars observed in Band 7. Given the depth of our dataset, this result is still consistent with what has been observed around radio-quiet quasars. Future higher spatial-resolution observations, over a broader frequency range, of high−zRL quasars hosts will allow us to further improve our understanding of the physics of these sources. 

We present bolometric luminosities, black hole masses, and Eddington ratios for 42 luminous quasars at z  ≳ 6 using high signal-to-noise ratio VLT/X-shooter spectra, acquired as part of the enlarged ESO Large Programme XQR-30 . In particular, we derived the bolometric luminosities from the rest-frame 3000 Å luminosities using a bolometric correction from the literature, as well as the black hole masses by modeling the spectral regions around the C  IV 1549 Å and the Mg  II 2798 Å emission lines, with scaling relations calibrated in the Local Universe. We find that the black hole masses derived from both emission lines are in the same range and the scatter of the measurements agrees with expectations from the scaling relations. The Mg  II -derived masses are between ∼(0.8−12) ×10 9   M ⊙ and the derived Eddington ratios are within ∼0.13−1.73, with a mean (median) of 0.84(0.72). By comparing the total sample of quasars at z  > 5.8, from this work and from the literature, to a bolometric luminosity distribution-matched sample at z  ∼ 1.5, we find that quasars at high redshift host slightly less massive black holes, which accrete slightly more rapidly than those at lower z , with a difference in the mean Eddington ratios of the two samples of ∼0.27. These findings are in agreement with the results of recent works in the literature.