First detection of ultra-fast outflows in a quiescent galaxy
Abstract
Outflows in active galactic nuclei (AGN) are recognized as a fundamental mechanism driving the co-evolution of supermassive black holes (SMBHs) and their host galaxies. Although powerful outflows are frequently detected in gas-rich, active star-forming galaxies, their existence and potential impact within gas-poor, quiescent galaxies remain poorly understood. We report the first detection of a powerful ultra-fast outflow (UFO) in a nearby quiescent galaxy KUG 1208+386, providing a multiscale analysis of AGN winds from nuclear to galactic scales. We detect a nuclear X-ray UFO with a velocity of vout ≈ −0.07c and a kinetic power of ĖUFO=(0.8−−6.5) × 1043erg/s, sufficient to drive effective AGN feedback (ĖUFO/LEdd=(1−−8)%) and far exceeding the galactic [OIII] outflow power ∼ 1040 erg/s. Host galaxy analysis reveals a massive quiescent system (specific star formation rate ∼3×10−12yr−1) that has been quenched ∼9 Gyr ago. The central AGN is obscured by a line-of-sight (LOS) column density of log (NHLOS/cm−2)∼23 and the circumnuclear scattering material is Compton-thick log(NHscatter/cm−2)=24.7+0.8−0.5. The discovery of a nuclear UFO in a long-quenched massive galaxy challenges the paradigm that UFOs are exclusive to gas-rich, star-forming systems, suggesting instead that they are governed by the local circumnuclear environments, rather than the global gas reservoir. Our results indicate that episodic, powerful winds can maintain the quiescent state of KUG 1208+386 over Gyr timescales, supporting a wind-driven `maintenance' mode of AGN feedback that is distinct from the classical jet mode.
Versions
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BibTeX
@misc{xu2026first,
title = {{First detection of ultra-fast outflows in a quiescent galaxy}},
author = {Yerong Xu and Malgorzata Siudek and Victor Rodríguez Morales and Mar Mezcua and Hai-cheng Feng and Ciro Pinto and James N. Reeves and Stefano Bianchi and Valentina Braito and Luigi C. Gallo},
howpublished = {arXiv},
year = {2026},
month = jul,
doi = {10.48550/arxiv.2607.06844},
eprint = {2607.06844},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.06844},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - First detection of ultra-fast outflows in a quiescent galaxy
AU - Yerong Xu
AU - Malgorzata Siudek
AU - Victor Rodríguez Morales
AU - Mar Mezcua
AU - Hai-cheng Feng
AU - Ciro Pinto
AU - James N. Reeves
AU - Stefano Bianchi
AU - Valentina Braito
AU - Luigi C. Gallo
PY - 2026
DA - 2026/07/07
PB - arXiv
DO - 10.48550/arxiv.2607.06844
UR - https://arxiv.org/abs/2607.06844
AB - Outflows in active galactic nuclei (AGN) are recognized as a fundamental mechanism driving the co-evolution of supermassive black holes (SMBHs) and their host galaxies. Although powerful outflows are frequently detected in gas-rich, active star-forming galaxies, their existence and potential impact within gas-poor, quiescent galaxies remain poorly understood. We report the first detection of a powerful ultra-fast outflow (UFO) in a nearby quiescent galaxy KUG 1208+386, providing a multiscale analysis of AGN winds from nuclear to galactic scales. We detect a nuclear X-ray UFO with a velocity of v_out ≈ −0.07c and a kinetic power of Ė_UFO=(0.8−−6.5) × 10^43erg/s, sufficient to drive effective AGN feedback (Ė_UFO/L_Edd=(1−−8)%) and far exceeding the galactic [OIII] outflow power ∼ 10^40 erg/s. Host galaxy analysis reveals a massive quiescent system (specific star formation rate ∼3×10^−12yr^−1) that has been quenched ∼9 Gyr ago. The central AGN is obscured by a line-of-sight (LOS) column density of log (N_H^LOS/cm^−2)∼23 and the circumnuclear scattering material is Compton-thick log(N_H^scatter/cm^−2)=24.7^+0.8_−0.5. The discovery of a nuclear UFO in a long-quenched massive galaxy challenges the paradigm that UFOs are exclusive to gas-rich, star-forming systems, suggesting instead that they are governed by the local circumnuclear environments, rather than the global gas reservoir. Our results indicate that episodic, powerful winds can maintain the quiescent state of KUG 1208+386 over Gyr timescales, supporting a wind-driven `maintenance' mode of AGN feedback that is distinct from the classical jet mode.
ER -