The WISSHFUL program

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Abstract
We present the first results from the WISSHFUL program, an XMM-Newton heritage program targeting luminous quasi-stellar objects (QSOs) at cosmic noon. We report on recent simultaneous XMM-Newton and NuSTAR observations of the super-Eddington accreting quasar WISSH13 at z=3.294, which provide the highest-quality broadband X-ray spectrum to date for a non-lensed QSO at this redshift. Physical modeling of the continuum reveals a soft photon index (Γ ∼ 2) and strong reflection ( R ~ 1.4-1.8), despite the weak narrow Fe emission, and a low high-energy cutoff ( E cut ∼ 60-80 keV, kT e = 15-20 keV, depending on the model adopted). Most notably, we detect two significant absorption features (at confidence levels of 96.7% and 98.9%, respectively) at ∼7.5 and ∼10 keV in the rest-frame, interpreted as a blueshifted blend of Fe XXV He α and Fe XXVI Ly α . These features indicate the presence of two kinematic components of a highly ionized, high-column ultrafast outflow (UFO) with a velocity of v out ∼ 0.1 c and v out ∼ 0.3 c , respectively. The slower wind is consistently detected in an archival 2017 XMM-Newton observation, whereas the faster wind is detected only in 2024. This stratified and variable wind exhibits extreme energetics, with a mass outflow rate of M out ∼ 20 M ⊙ /yr (corresponding to 15% M acc ) for each component, and a kinetic power on the order of ∼1 and ∼10% of the bolometric luminosity, respectively. While this represents one of the most powerful UFOs ever detected, its kinetic power is a similar fraction of the QSO’s bolometric luminosity compared to lower-redshift active galactic nuclei. We present several theoretical frameworks to explain the peculiar accretion and ejection properties of this remarkable QSO at cosmic noon.

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