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The ALMA view of the high redshift relation between supermassive black holes and their host galaxies

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Pensabene, A 
Carniani, S 
Perna, M 
Cresci, G 
Decarli, R 


This work aims at studying the MBHMdyn relation of a sample of 2<z<7 quasars by constraining their host galaxy masses through a full kinematical modelling of the cold gas kinematics thus avoiding all possible biases and effects introduced by the rough virial estimates usually adopted so far. For this purpose we retrieved public observations of 72 quasar host galaxies observed in [CII]158μm or CO transitions with the Atacama Large Millimeter Array (ALMA). We then selected those quasars whose line emission is spatially resolved and performed a kinematic analysis on ALMA observations. We estimated the dynamical mass of the systems by modelling the gas kinematics with a rotating disc taking into account geometrical and instrumental effects. Our dynamical mass estimates, combined with MBH obtained from literature and our own new CIVλ1550 observations have allowed us to investigate the $ M_{BH}/M_{dyn}$ in the early Universe. Overall we obtained a sample of 10 quasars at z∼2−7 in which line emission is detected with high SNR (>5−10) and the gas kinematics is spatially resolved and dominated by ordered rotation. The estimated dynamical masses place 6 out of 10 quasars above the local relation yielding to a MBH/Mdyn ratios ∼10× higher than those estimated in low-z galaxies. On the other hand we found that 4 quasars at z∼4−6 have dynamical-to-BH mass ratios consistent with what is observed in early type galaxies in the local Universe.



galaxies: evolution, galaxies: high-redshift, galaxies: kinematics and dynamics, quasars: supermassive black holes

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Astronomy and Astrophysics

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EDP Sciences


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European Research Council (695671)
Science and Technology Facilities Council (ST/M001172/1)