Irradiation of accretion discs in active galactic nuclei due to the presence of a warm absorber

Loska, Z.; Szczerba, R.

doi:10.1111/j.1365-2966.2004.08387.x

Cited by 23 publications

(28 citation statements)

References 116 publications

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“…Hence, it seems more likely that the disc is directly illuminated, where the constant illumination fraction, Ω out /2π, is a natural consequence of a constant disc geometry. Detailed calculations show that the (steady‐state) disc shape is convex, so a pure disc cannot self‐illuminate (Dubus et al 1999), but the self‐consistent X‐ray illuminated disc vertical structure is more complex, and can lead to a thicker disc (Jimenez‐Garate, Raymond & Liedahl 2002; Loska, Czerny & Szczerba 2004). Alternatively, the disc can be warped, so that the outer edge is directly illuminated.…”

Section: Discussionmentioning

confidence: 99%

Reprocessing of X-rays in the outer accretion disc of the black hole binary XTE J1817−330

Gierliński

Done

Page

2009

Monthly Notices of the Royal Astronomical Society

161

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We build a simple model of the optical/ultraviolet (UV) emission from irradiation of the outer disc by the inner disc and coronal emission in black hole binaries. We apply this to the broad‐band Swift data from the outburst of the black hole binary XTE J1817−330 to confirm previous results that the optical/UV emission in the soft state is consistent with a reprocessing a constant fraction of the bolometric X‐ray luminosity. However, this is very surprising as the disc temperature drops by more than a factor of 3 in the soft state, which should produce a marked change in the reprocessing efficiency. The easiest way to match the observed constant reprocessed fraction is for the disc skin to be highly ionized (as suggested 30 yr ago by van Paradijs), so that the bulk of the disc flux is reflected and only the hardest X‐rays heat the disc. The constant reprocessed fraction also favours direct illumination of the disc over a scattering origin as the optical depth/solid angle of any scattering material (wind/corona) over the disc should decrease as the source luminosity declines. By contrast, the reprocessed fraction increases very significantly (by a factor of ∼6) as the source enters the hard state. This dramatic change is not evident from X‐ray/UV flux correlations as it is masked by bandpass effects. However, it does not necessarily signal a change in emission, for example, the emergence of the jet dominating the optical/UV flux as the reflection albedo must change with the dramatic change in spectral shape.

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Section: Discussionmentioning

confidence: 99%

Reprocessing of X-rays in the outer accretion disc of the black hole binary XTE J1817−330

Gierliński

Done

Page

2009

Monthly Notices of the Royal Astronomical Society

161

200

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“…Even if the very centre produces most of the X‐ray emission, the outer disc may not ‘see’ much of it. Instead, a large‐scale backscattering matter may be located at significant height above the disc, thus increasing the light‐crossing time two to three times (Loska et al 2004; Czerny & Janiuk 2007, see also their fig. 6).…”

Section: Discussionmentioning

confidence: 99%

Studying X-ray reprocessing and continuum variability in quasars: PG 1211+143

Bachev

Grupe

Boeva

et al. 2009

Monthly Notices of the Royal Astronomical Society

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We present the results from a monitoring campaign of the Narrow‐Line Seyfert 1 galaxy PG 1211+143. The object was monitored with ground‐based facilities (UBVRI photometry; from 2007 February to July) and with Swift[X‐ray photometry/spectroscopy and ultraviolet (UV)/optical photometry; between 2007 March and May]. We found PG 1211+143 in a historical low X‐ray flux state at the beginning of the Swift monitoring campaign in 2007 March. It is seen from the light curves that while violently variable in X‐rays, the quasar shows little variations in optical/UV bands. The X‐ray spectrum in the low state is similar to other narrow‐line Seyfert 1 galaxies during their low states and can be explained by a strong partial covering absorber or by X‐ray reflection on to the disc. With the current data set, however, it is not possible to distinguish between both scenarios. The interband cross‐correlation functions indicate a possible reprocessing of the X‐rays into the longer wavelengths, consistent with the idea of a thin accretion disc, powering the quasar. The time lags between the X‐ray and the optical/UV light curves, ranging from ∼2 to ∼18 d for the different wavebands, scale approximately as ∼λ4/3, but appear to be somewhat larger than expected for this object, taking into account its accretion disc parameters. Possible implications for the location of the X‐ray irradiating source are discussed.

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“…Loska et al, 2004). The disk effective temperature, T eff , at a given radius, r, is thus basically determined by the black hole mass and accretion rate.…”

Section: Failed Radiatively Accelerated Dust-driven Outflow (Frado) Mmentioning

confidence: 99%

The dust origin of the Broad Line Region and the model consequences for AGN unification scheme

Modzelewska

Petrogalli

Pych

et al. 2015

Advances in Space Research

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We propose a very simple physical mechanism responsible for the formation of the Low Ionization Line part of the Broad Line Region in Active Galactic Nuclei. It explains the scaling of the Broad Line Region size with the monochromatic luminosity, including the exact slope and the proportionality constant, seen in the reverberation studies of nearby sources. The scaling is independent from the mass and accretion rate of an active nucleus. The mechanism predicts the formation of a dust-driven wind in the disk region where the local effective temperature of a non-illuminated accretion disk drops below 1000 K and allows for dust formation. We explore now the predictive power of the model with the aim to differentiate between this model and the previously proposed mechanisms of the formation of the Broad Line Region. We discuss the expected departures from the universal scaling at long wavelength, and the role of the inclination angle of the accretion disk in the source. We compare the expected line profiles with Mg II line profiles in the quasars observed by us with the SALT telescope. We also discuss the tests based on the presence or absence of the broad emission lines in low luminosity active galaxies. Finally, we discuss the future tests of the model to be done with expected ground-based observations and satellite missions.

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Irradiation of accretion discs in active galactic nuclei due to the presence of a warm absorber

Cited by 23 publications

References 116 publications

Reprocessing of X-rays in the outer accretion disc of the black hole binary XTE J1817−330

Reprocessing of X-rays in the outer accretion disc of the black hole binary XTE J1817−330

Studying X-ray reprocessing and continuum variability in quasars: PG 1211+143

The dust origin of the Broad Line Region and the model consequences for AGN unification scheme

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