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 «L_bol» =10^47.5 erg s^-1 and «z» = 2.5. For seven sources with strong X-ray detections, we perform spectral analyses. These find a median X-ray luminosity of «L_{2-10 keV}» = 10^45.1 erg s^-1, comparable to the most powerful X-ray quasars known. The gas column densities are N_H = (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_{6 μm}) and bolometric luminosities (L_bol), in agreement with findings for other luminous quasar samples. For instance, the X-ray to bolometric corrections range from κ_bol ≈ 50 to 3000. The moderate absorption levels and accretion rates close to the Eddington limit («λ_Edd» =1.06) are in agreement with a quasar blowout phase. Indeed, we find that the HRQs lie in the forbidden region of the N_H-λ_Edd 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.