X-ray Observations of Luminous Dusty Quasars at z > 2

G. B. Lansbury; M. Banerji; A. C. Fabian; M. J. Temple

doi:10.1093/mnras/staa1220

paper

X-ray Observations of Luminous Dusty Quasars at z > 2

arXiv:1910.00602 · doi:10.1093/mnras/staa1220

Abstract

We present new X-ray observations of luminous heavily dust-reddened quasars (HRQs) selected from infrared 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 $⟨ L_{bol} ⟩ = 1 0^{47.5}$ erg/s and $⟨ z ⟩ = 2.5$ . For the seven sources with strong X-ray detections, we perform spectral analyses. These find a median X-ray luminosity of $⟨ L_{2 - 10 keV} ⟩ = 1 0^{45.1}$ erg/s, comparable to the most powerful X-ray quasars known. The gas column densities are $N_{H} = (1$ - $8) \times 1 0^{22}$ 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-infrared ( $L_{6 μ m}$ ) and bolometric luminosities ( $L_{bol}$ ), in agreement with findings for other luminous quasar samples. For instance, the X-ray to bolometric corrections range from $κ_{bol} \approx 50$ - $3000$ . 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 $1 0^{5}$ years. The wider properties, including [OIII] narrow-line region kinematics, broadly agree with this interpretation.

arXiv commentIn press. Accepted for publication in MNRAS

X-ray Observations of Luminous Dusty Quasars at z > 2

Abstract

References in corpus (117)

Cited by in corpus (27)