Motivated by a number of X-ray observations of active galactic nuclei (AGNs) that exhibit a potential signature of ultra-fast inflows (UFIs), we consider in this work a scenario that UFIs can be physically identified as weakly-magnetized hydrodynamic accretion flows that is guided and channeled by poloidal magnetic field into low-to-mid latitude above the equatorial disk. In the context of general relativistic hydrodynamics (GRHD) under a weak-field limit in Kerr spacetime, we present a set of preliminary results by numerically calculating the physical property of GRHD flows (e.g. kinematics and density distribution) in an effort to simulate redshifted absorption line spectra. Our model demonstrates that such GRHD accretion off the equatorial plane (i.e. v\gsim0.1c where c is the speed of light in the vicinity of AGN closer than ∼100 \sw radii) can manifest itself as UFIs in the form of redshifted absorption signature assuming the observed characteristics such as column density of NH∼1023 cm−2 and ionization parameter of log(ξ[ergcms−1])∼3 as also seen in recent multi-epoch {\it NuSTAR} observations among other data.
@article{arxiv.2601.04141,
title = {Implications of Non-equatorial Relativistic Accretion Flows for Ultra-Fast Inflows in AGNs},
author = {Keigo Fukumura and Alessandro Peca and Roberto Serafinelli and Mauro Dadina},
journal= {arXiv preprint arXiv:2601.04141},
year = {2026}
}