Unveiling the dynamics of the ultra-fast outflow in IRAS 13224-3809 with X-ray spectroscopy

IRAS 13224-3809 is one of the most intensively studied narrow-line Seyfert 1 galaxies, with a rich store of literature reporting diverse and, occasionally, contrasting interpretations of its complex X-ray spectra and variability. Notably, a fast and variable ultrafast outflow (UFO) was discovered in this source, sparking debate over its nature and driving mechanisms. Motivated by these open questions, we present a systematic time-, and flux-resolved reanalysis of the full 2016 XMM-Newton (1.5 Ms) and NuSTAR (500 ks) datasets, employing a careful background treatment and equal-count spectral selections. We uniformly applied three spectral models, including photoionized absorption, broad emission, and relativistic reflection, to all intervals. We unambiguously confirm the presence of a strong, variable outflow with velocities exceeding 0.2c. We also find that models including absorption consistently reveal robust physical trends: a velocity-luminosity correlation of the UFO, persistently large line widths, and no compelling equivalent-width-flux anticorrelation. When emission or reflection components are included, the significance of the absorption features decreases, but significant UFO detections remain in most intervals. We also report clear evidence of rapid acceleration of the wind in response to X-ray flares, with the outflow carrying sufficient momentum and kinetic power to drive efficient active galactic nucleus feedback. The observed rapid response favors magnetic driving, analogous to coronal mass ejections, over radiative acceleration. Our results reconcile contrasting previous claims and underline the need for high-resolution spectroscopy to resolve the wind substructure. The observed UFO variability and structure are consistent with a multiphase, clumpy wind produced by thermal and hydrodynamic instabilities, with magnetic reconnection providing the rapid acceleration mechanism.