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The extreme velocities and high ionization states of ultra-fast outflows (UFOs) make them a promising candidate for AGN feedback on the evolution of the host galaxy. However, their exact underlying driving mechanism is not yet fully…

Ultra-fast outflows (UFOs) are highly ionized, mildly relativistic winds seen in the X-ray spectra of active galactic nuclei (AGN) and are thought to contribute to AGN feedback and galaxy evolution. We investigate UFO signatures by…

Ultra Fast Outflows (UFOs) are powerful, highly ionized winds launched from the innermost regions of Active Galactic Nuclei (AGNs), reaching velocities of 0.03 -- 0.3 c and playing a key role in AGN feedback. We present a photoionization…

High Energy Astrophysical Phenomena · Physics 2025-11-19 Xin Xiang , Jon M. Miller , Ehud Behar , W. N. Brandt , Luigi Gallo , Doyee Byun , Elena Gallo

Ultra-fast outflows (UFOs) have been detected in the high-quality X-ray spectra of a number of active galactic nuclei (AGN) with fairly high accretion rates and are thought to significantly contribute to the AGN feedback. After a decade of…

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. The AGN feedback…

Relativistically blueshifted absorption features of highly ionised ions, the so-called ultra-fast outflows (UFOs), have been detected in the X-ray spectra of a number of accreting supermassive black holes. If these features truly originate…

High Energy Astrophysical Phenomena · Physics 2020-06-03 P. Kosec , A. Zoghbi , D. J. Walton , C. Pinto , A. C. Fabian , M. L. Parker , C. S. Reynolds

X-ray evidence for ultra-fast outflows (UFOs) has been recently reported in a number of local AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large…

High Energy Astrophysical Phenomena · Physics 2012-08-27 F. Tombesi , M. Cappi , R. M. Sambruna , J. N. Reeves , C. S. Reynolds , V. Braito , M. Dadina

IRAS 13224-3809 is one of the most intensively studied narrow-line Seyfert 1 galaxies, with a rich literature reporting diverse and sometimes contrasting interpretations of its complex X-ray spectra and variability. Notably, a fast and…

We use MUSE adaptive optics (AO) data in Narrow Field Mode to study the properties of the ionised gas in MR 2251-178 and PG 1126-041, two nearby (z~0.06) bright quasars hosting sub-pc scale Ultra Fast Outflows (UFOs) detected in the X-ray…

During the last decade, strong observational evidence has been accumulated for the existence of massive, high velocity winds/outflows (aka Ultra Fast Outflows, UFOs) in nearby AGNs and in more distant quasars. Here we briefly review some of…

High Energy Astrophysical Phenomena · Physics 2013-01-31 M. Cappi , F. Tombesi , M. Giustini

Ultrafast outflows (UFOs) have recently been found in the spectra of a number of active galactic nuclei (AGN) and are strong candidates for driving AGN feedback. 1H0707-495 is a highly accreting narrow line Seyfert 1 and the second most…

High Energy Astrophysical Phenomena · Physics 2018-09-05 P. Kosec , D. J. K. Buisson , M. L. Parker , C. Pinto , A. C. Fabian , D. J. Walton

The detection of blue-shifted absorption lines likely associated with ionized Iron K-shell transitions in the X-ray spectra of many Active Galactic Nuclei (AGN) suggests the presence of a highly ionized gas outflowing with mildly…

Ultra-fast outflows (UFOs) are seen in many AGN, giving a possible mode for AGN feedback onto the host galaxy. However, the mechanism(s) for the launch and acceleration of these outflows are currently unknown, with UV line driving…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Kouichi Hagino , Hirokazu Odaka , Chris Done , Poshak Gandhi , Shin Watanabe , Masao Sako , Tadayuki Takahashi

XMM-Newton and Suzaku spectra of AGN have revealed highly ionized gas, in the form of absorption lines from H-like and He-like Fe. Some of these absorbers, "Ultra Fast Outflows (UFOs)", have radial velocities of up to 0.25c. We have…

Astrophysics of Galaxies · Physics 2018-01-10 S. B. Kraemer , F. Tombesi , M. C. Bottorff

Using two-dimensional radiation hydrodynamic simulations, we investigate origin of the ultra fast outflows (UFOs) that are often observed in luminous active galactic nuclei (AGNs). We found that the radiation force due to the spectral lines…

High Energy Astrophysical Phenomena · Physics 2016-01-20 Mariko Nomura , Ken Ohsuga , Hiroyuki R. Takahashi , Keiichi Wada , Tessei Yoshida

Recent X-ray observations show absorbing winds with velocities up to mildly-relativistic values of the order of ~0.1c in a limited sample of 6 broad-line radio galaxies. They are observed as blue-shifted Fe XXV-XXVI K-shell absorption…

High Energy Astrophysical Phenomena · Physics 2015-06-22 F. Tombesi , F. Tazaki , R. F. Mushotzky , Y. Ueda , M. Cappi , J. Gofford , J. N. Reeves , M. Guainazzi

Among a number of active galactic nuclei (AGNs) that drive ionized outflows in X-rays, a low-redshift (z = 0.184) quasar, PDS 456, is long known to exhibit one of the exemplary ultra-fast outflows (UFOs). However, the physical process of…

High Energy Astrophysical Phenomena · Physics 2018-09-19 Keigo Fukumura , Demosthenes Kazanas , Chris Shrader , Ehud Behar , Francesco Tombesi , Ioannis Contopoulos

Powerful outflows from active galactic nuclei (AGN) can significantly impact the gas reservoirs of their host galaxies. However, it is still unclear how these outflows can propagate from the very central regions of galaxies to their…

X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet AGNs. In the previous paper of this series we defined UFOs as those absorbers with an outflow velocity higher…

High Energy Astrophysical Phenomena · Physics 2015-05-30 F. Tombesi , M. Cappi , J. N. Reeves , G. G. C. Palumbo , V. Braito , M. Dadina

Ultra-fast outflows (UFOs) play a key role in the AGN feedback mechanism. It is therefore important to fully characterize their location and energetics. We study the UFO in the latest XMM-Newton archival observation of the NLSy1 galaxy PG…

High Energy Astrophysical Phenomena · Physics 2021-01-27 M. Laurenti , A. Luminari , F. Tombesi , F. Vagnetti , R. Middei , E. Piconcelli
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