An Exceptionally Powerful, Radiatively Driven Ultrafast Outflow in the Rapidly Accreting AGN REJ1034+396

Abstract: We report the analysis of ~1Ms of XMM-Newton observations of the rapidly accreting active galactic nucleus REJ1034+396. The 0.3-9 keV EPIC-pn spectra are well described by a model consisting of steep continuum emission from the corona accompanied by relativistically-blurred reflection from a highly ionized accretion disk. The source is known to exhibit strong excess soft X-ray emission, which we show is well represented by thermal disk photons Comptonized by a warm plasma spanning the inner accretion flow. Additionally, the EPIC-pn data provide compelling evidence ($\Delta C\sim60$ for 4 additional parameters) for the presence of an ultrafast outflow (UFO) with a line-of-sight velocity $v/c=0.307^{+0.001}_{-0.005}$, and an emission signature consistent with reflection of the corona from modestly ionized, outflowing gas. The simultaneous $0.5-2.5$\,keV RGS spectra show clear absorption lines. Modelling of these data confirms the presence of the UFO and constrains its equivalent hydrogen column density, log $N_\mathrm{H}/$(atom cm$^{-2}$) = $21.7^{+0.1}_{-0.2}$. The RGS data also reveal at least two warm absorber components with a modest outflow velocity ($1680^{+40}_{-50}$ km/s). The measured properties and time evolution of the UFO in REJ1034+396 suggest that it is formed from collisionally ionized plasma, launched from the disk surface and accelerated by radiation pressure. The high terminal velocity and substantial absorbing column density imply that the outflow carries sufficient momentum and energy to transform its environment, being capable of driving out essentially all dust and gas it interacts with along the line of sight, even if the AGN were initially surrounded by a Compton thick absorber.