Unification of X-ray winds in Seyfert galaxies: from ultra-fast outflows to warm absorbers

By F. Tombesi, M. Cappi, J. Reeves, R. Nemmen, V. Braito, M. Gaspari, C. S. R. NASAGoddard, U. Maryland, College Park, INAF-IASF Bologna and 3 more. 2012

241 citations recorded by the source corpus.

The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60%, consistent with previous studies. The fraction of sources with UFOs is >34%, >67% of which also show WAs. The large dynamic range obtained when considering all the absorbers together, spanning several orders of magnitude in ionization, column, velocity, and distance allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. In all the cases, the absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. These evidences strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The UFOs are likely launched from the inner accretion disc and the WAs at larger distances, such as the outer disc and/or torus. We argue that the observed parameters and correlations are, to date, consistent with both radiation pressure through Compton scattering and MHD processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, show a sufficiently high mechanical power (at least �0.5% of the bolometric luminosity) to provide a significant contribution to AGN feedback and thus to the evolution of the host galaxy. In this regard, we find possible evidences for the interaction of the AGN wind with the surrounding environment on large-scales.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/e77074785f39b610041e7e5d88bffca196a51dd9

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Nuclear and High Energy Physics

Citations in the corpus

Determining Inclinations of Active Galactic Nuclei Via Their Narrow-Line Region Kinematics (2012, background): “…but not the highly-ionized ultra-fast outflow (UFO) absorbers detected in the Fe Kshell absorption lines, because the two types are quite distinct in terms of ionization parameter, outflow velocity, distance from the central AGN, and column density (Tombesi et al. 2013, and references therein).”
AGN wind scaling relations and the co-evolution of black holes and galaxies (2017, background): “X-ray winds Most X-ray winds are from the compilation of Tombesi et al. (2013), which include fast UFOs and slower warm absorbers.”
Star-forming galaxies as the origin of diffuse high-energy backgrounds: gamma-ray and neutrino connections, and implications for starburst history (2014, background): “At the dissipation radius R ∼ 100 pc, the outflow velocity is of the order of Vw ∼ 1000 km s−1 [88].”
Gravitational torque-driven black hole growth and feedback in cosmological simulations (2016, methodology): “…simulations, we explore the effects of outflows with parameters similar to observed fast nuclear outflows (vout = 104 km s−1, Ṗout = Lbol/c; e.g. Tombesi et al. 2013; Nardini et al. 2015) and galaxy-scale AGN-driven winds (vout = 103 km s−1, Ṗout = 20 Lbol/c; e.g. Faucher-Giguère & Quataert…”
Discovery of extreme [O III] λ5007 Å outflows in high-redshift red quasars (2015, background): “…techniques which trace different components of the wind (e.g. Arav et al. 2008; Chartas et al. 2009; Nesvadba et al. 2010; Ogle et al. 2010; Rupke & Veilleux 2013a; Tombesi et al. 2013; Veilleux et al. 2013a; Greene et al. 2014a; Sun et al. 2014; Crichton et al. 2016; Nardini et al. 2015).”
BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift/BAT 70-month AGN Catalog (2017, background): “These values are in good agreement with what was found by previous studies of warm absorbers (e.g., Tombesi et al. 2013 and references therein).”
Powerful Outflows and Feedback from Active Galactic Nuclei (2015, background): “It is interesting to note that similar shocking of fast outflows provides a natural link between UFOs and the equally common ‘warm absorbers’ in AGN (Tombesi et al. 2013).”