The origin of the broad line region in active galactic nuclei

By B. Czerny, K. Hryniewicz. 2010

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Aims. Although broad emission lines are the most reliable signature of the nuclear activity of a galaxy and the location of the emitting material is well measured by the reverberation method, the physical cause of the formation of the broad line region remains unclear. We attempt to place some constraints on its origin. Methods. We study the properties of the accretion disk underlying the broad line region. Results. We find that the effective temperature at the disk radius corresponding to the location of the broad line region, as inferred from the Hβ line, is universal in all monitored sources and equal to 1000 K. This value is close to the limiting value that permits the existence of the dust. Conclusions. The likely origin of the low ionization part of the broad line region is the strong local dusty wind from the disk. This wind becomes exposed to the irradiation by the central regions when moving higher above the disk surface and subsequently behaves like a failed wind, thus leading to a local mixture of inflow and outflow. This may provide the physical explanation of the turbulence needed both to smooth the line profiles as well as provide additional mechanical heating.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/087635ad0b7f06cc07b71c64f67c9a3530530750

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Citations in the corpus

A diversity of dusty AGN tori - Data release for the VLTI/MIDI AGN Large Program and first results for 23 galaxies (2013, background): “Current dynamical models of the torus see it either made up from outflowing (e.g. Elitzur & Shlosman, 2006; Czerny & Hryniewicz, 2011; Gallagher et al., 2013) material that is part of a wind blown off from the accretion disk or as an inflowing structure whose scale-height may be provided by…”
THE MAN BEHIND THE CURTAIN: X-RAYS DRIVE THE UV THROUGH NIR VARIABILITY IN THE 2013 ACTIVE GALACTIC NUCLEUS OUTBURST IN NGC 2617 (2013, background): “Czerny & Hryniewicz (2011) offer a third model.”
Revisiting the Unified Model of Active Galactic Nuclei (2015, background): “Other proposed mechanisms to maintain a thick structure involve UV, optical and IR radiation pressure (e.g. Hönig & Beckert 2007, Krolik 2007, Czerny & Hryniewicz 2011, Wada 2012), magnetic winds (Emmering, Blandford & Shlosman 1992; Konigl & Kartje 1994; Elitzur & Shlosman 2006), and SF in the…”
First X-ray-based statistical tests for clumpy-torus models: eclipse events from 230 years of monitoring of Seyfert AGN (2014, background): “Similarly, Czerny & Hryniewicz (2011) proposed a turbulent, dusty, disk wind as the origin for the low-ionization region of the BLR: clouds rise from the disk, intense external radiation heats the gas and dust sublimates.”