A relativistic inflow candidate in a quasar at cosmic noon

Cosmic noon (z about2) marks the peak epoch of cosmic star formation and black hole accretion activity, where strong accretion and outflows are expected. We report two candidate absorption features in the XMM-Newton spectrum of the quasar WISEA J094835.95+432302.6 at z=1.893. Two redshifted features occur at rest-frame energies of about4.65 and about5.75 keV with confidence levels of 99.3% and 94.1%, respectively, estimated from Monte Carlo (MC) simulations considering the look-elsewhere effect. These features can be explained by the Fe XXV/XXVI K-shell transitions from one ultra-fast inflow (UFI) with an apparent velocity of 0.37+0.02-0.01c. If confirmed by follow-up XMM-Newton observations, these detections would extend reported UFI candidates from the local Universe to cosmic noon, offering a rare laboratory for black hole accretion at the peak of their growth.