Discovery of ultra-fast outflows with v_out> 0.3c in local bright active galactic nuclei

¹ Dipartimento di Fisica e Astronomia “Augusto Righi”, Università di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
² INAF – OAS, Osservatorio di Astrofisica e Scienza dello Spazio Bologna, Via Piero Gobetti, 93/3, 40129 Bologna, Italy
³ European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201 AZ, Noordwijk, The Netherlands
⁴ INAF – Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monte Porzio Catone, Italy
⁵ INAF – Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Caveliere 100, I-00133 Roma, Italy
⁶ Astronomical Institute of the Czech Academy of Sciences, Boční II 1401/1, 14100 Praha 4, Czech Republic

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 28 November 2025
Accepted: 17 April 2026

Abstract

Context. Ultra-fast outflows (UFOs) are mildly relativistic (outflow velocity v_out > 0.1c) nuclear winds detected as blueshifted absorption lines from highly ionized, dense gas in the X-ray spectra of active galactic nuclei (AGNs). The AGN feedback mechanism is believed to be powered by these outflows, which can inject a large amount of energy and momentum into the surrounding interstellar medium, shaping the coevolution of the AGNs and their host galaxies.

Aims. We performed a systematic search and rigorous statistical assessment of the presence of UFOs in the 7 − 12 keV band, in a sample of bright local AGNs. This study also aims to understand whether the presence and characteristics of UFOs depend on the state of the sources, by studying the relations between the incidence of UFOs and the accretion properties of AGNs.

Methods. We collected X-ray spectroscopic flux-limited XMM-Newton data of 33 observations of local (z < 0.2) type 1 AGNs. We modeled their spectra in the 2 − 12 keV band using a combination of direct-continuum and reflection components and searched for absorption features. This represents the first systematic search for UFOs up to 12 keV. We performed Monte Carlo (MC) simulations to assess the statistical significance of the detected lines.

Results. We report strong detections of UFOs in six sources of the sample at the ≥95% confidence level via MC simulations, corresponding to a fraction of ∼18% in our sample. From the observed energies of each absorption line, we evaluated the respective wind velocities, which in some cases exceed 40% of the speed of light. The velocity distribution found in this work is therefore shifted to higher energies than those found in previous searches for UFOs in local sources, which were limited to 10 keV. Moreover, our analysis shows no correlation between the accretion properties of the super massive black holes (SMBHs) and the presence of winds. Finally, the comparison with previous studies of nuclear winds in local AGNs highlights the temporal variability of UFOs.