On the location and composition of the dust in the MCG–6-30-15 warm absorber

Ballantyne, D. R.; Weingartner, Joseph C.; Murray, Norman

doi:10.1051/0004-6361:20031166

Cited by 21 publications

(25 citation statements)

References 55 publications

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“…However, this is not the case for MRK 766, where the optical data clearly appear absorbed even with a larger host galaxy column. We suggest that these data are indeed strongly reddened, perhaps from a dust entrained in the narrow warm absorber systems in a similar manner to MCG−6‐30‐15 (Reynolds 1997; Kraemer et al 2000; Ballantyne, Weingartner & Murray, 2003).…”

Section: Simultaneous Spectral Energy Distributions (Seds)mentioning

confidence: 70%

An absorption origin for the soft excess in Seyfert 1 active galactic nuclei

Middleton

Done

Gierliński

2007

Monthly Notices of the Royal Astronomical Society

100

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The soft excess seen in the X‐ray spectra of many active galactic nuclei (AGN) can be well modelled by reflection from a partially ionized accretion disc. However, this often requires extreme parameters, both in terms of the underlying space–time and the reflection geometry, and requires that the disc is far from hydrostatic equilibrium. An alternative model uses similarly partially ionized, velocity smeared material but from an accretion disc wind seen in absorption. We explicitly compare these two models for the origin of the soft excess using XMM–Newton data for PG QSOs and narrow‐line Seyfert 1 galaxies (NLS1s). We find that while reflection and absorption give comparably good fits to the data, the absorption model allows a much clearer correspondence with the stellar mass black holes. All the objects are high mass accretion rate AGN, so should be analogous to the high/soft and very high states in black hole binaries. The intrinsic spectral indices derived from the absorption model are all consistent with a one‐to‐one mapping between spectral state and AGN type, with the NLS1s having softer spectra corresponding to the very high state, while the broad‐line AGN have Γ= 2 as expected for the high/soft state. By contrast, a few AGN have intrinsically hard spectra with the reflection model. While this supports an absorption interpretation of the soft excess, we note that the required Gaussian velocity dispersion of ≥0.2c (corresponding to an outflow velocity ≥0.4c) is too fast for a radiatively driven accretion disc wind and instead requires that the material is entrained in a magnetic outflow (jet). We also use the simultaneous optical monitor data to derive the ratio of disc to total accretion power which is another tracer of spectral state in X‐ray binaries. This does not always show that the disc in NLS1s contributes less than 80 per cent of the total power, as expected for a very high state. We suggest that this is an artefact of the standard disc models used to determine the disc luminosity in our fits. The disc seen in the very high state of black hole binaries is often observed to be distorted from the standard shape, and a similar effect in NLS1s could recover the one‐to‐one mapping between black hole binary spectral state and AGN type.

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Section: Simultaneous Spectral Energy Distributions (Seds)mentioning

confidence: 70%

An absorption origin for the soft excess in Seyfert 1 active galactic nuclei

Middleton

Done

Gierliński

2007

Monthly Notices of the Royal Astronomical Society

100

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“…The shortest variability timescale of ∼10 4 s has been detected in the warm absorber in MCG-6-30-15 (Otani et al 1996; see also Turner et al 2004) locating the plasma responsible for the Oviii edge within the distance of 10 17 cm from the nucleus. The spectral analysis of this source indicates that the highly ionized warm absorber is dust-free, with dust contribution in this source coming from a distant zone, hundreds of pc from the nucleus (Ballantyne et al 2003).…”

Section: Introductionmentioning

confidence: 88%

Modeling the warm absorber in active galactic nuclei

Różáńska¹,

Goosmann²,

Dumont³

2006

A&A

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We present a wide grid of models for the structure and transmission properties of warm absorbers in active galactic nuclei (AGN). Contrary to commonly used constant density models, our absorbing cloud is assumed to be under constant total (gas plus radiation) pressure. This assumption implies the coexistence of material at different temperatures and ionization states, which is a natural consequence of pressure and thermal equilibrium. Our photoionization code allows us to compute the profiles of the density, the temperature, the gas pressure, the radiation pressure and the ionization state across the cloud, and to calculate the radiative transfer of continuum and lines including Compton scattering. Therefore, equivalent widths of both saturated and unsaturated lines are properly modeled. For each pair of the incident spectrum slope and the ionization parameter at the cloud surface there is a natural upper limit to the total column densities of the cloud due to thermal instabilities. These maximum values are comparable to the observational constraints on the column density of warm absorbers which may give support to constant total pressure models. In all models we note considerable absorption around 6.4 keV which modifies the intrinsic relativistically broadened iron line profile originating in an accretion disk illuminated atmosphere. Our models can be applied to fitting the spectroscopic data from the XMM-Newton and Chandra satellites.

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“…The possible presence of the dust in the warm absorber is discussed in a number of papers (e.g. Komossa & Breitschwerdt 2000; Mason et al 2003; Ballantyne, Weingartner & Murray 2003).…”

Section: Methodsmentioning

confidence: 99%

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

Loska

Szczerba

2004

Monthly Notices of the Royal Astronomical Society

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The presence of a warm absorber of considerable optical depth is seen in many AGN. We show that this medium may significantly affect the optical/UV spectrum of an AGN by backscattering a fraction of the total radiation flux towards the disc surface. We consider in detail the case in which the disc extends down to a marginally stable orbit, all the emission comes from the disc surface, and the scattering medium forms a cone around the symmetry axis. Disc irradiation results in a much flatter optical/UV continuum than is predicted by standard disc models. The effect depends both on the total optical depth of the warm absorber and on the specific density distribution of this medium, so analysis of the optical/UV continuum allows constraints to be obtained for the warm absorber that are complementary to those obtained from the soft X‐ray data analysis. We give results for two example sources – RE J1034+396 and PG 1211+143, and for the bluest composite quasar spectrum of Richards et al. obtained from the SDSS.

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On the location and composition of the dust in the MCG–6-30-15 warm absorber

Cited by 21 publications

References 55 publications

An absorption origin for the soft excess in Seyfert 1 active galactic nuclei

An absorption origin for the soft excess in Seyfert 1 active galactic nuclei

Modeling the warm absorber in active galactic nuclei

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

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