X-ray observations of luminous dusty quasars at z > 2

We present new X-ray observations of luminous heavily dust-reddened quasars (HRQs) selected from infrared (IR) sky surveys. HRQs appear to be a dominant population at high redshifts and the highest luminosities, and may be associated with a transitional 'blowout' phase of black hole and galaxy co-evolution models. Despite this, their high-energy properties have been poorly known. We use the overall sample of 10 objects with XMM-Newton coverage to study the high-energy properties of HRQs at $langle$Lbol$rangle$ =1047.5 erg s-1 and $langle$z$rangle$ =2.5. For seven sources with strong X-ray detections, we perform spectral analyses. These find a median X-ray luminosity of $leftlangle L_{rm 2!-!10, keV} rightrangle = 10^{45.1}$ erg s-1, comparable to the most powerful X-ray quasars known. The gas column densities are NH = (1-8) × 1022 cm-2, in agreement with the amount of dust extinction observed. The dust-To-gas ratios are sub-Galactic, but are higher than found in local AGN. The intrinsic X-ray luminosities of HRQs are weak compared to the mid-IR ($L_{rm 6, mu m}$) and bolometric luminosities (Lbol), in agreement with findings for other luminous quasar samples. For instance, the X-ray to bolometric corrections range from κbol ≈ 50 to 3000. The moderate absorption levels and accretion rates close to the Eddington limit ($langle$λEdd$rangle$ =1.06) are in agreement with a quasar blowout phase. Indeed, we find that the HRQs lie in the forbidden region of the NH-λEdd plane, and therefore that radiation pressure feedback on the dusty interstellar medium may be driving a phase of blowout that has been ongoing for a few 105 yr. The wider properties, including [O iii] narrow-line region kinematics, broadly agree with this interpretation. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.