The Spatial Structure of an Accretion Disk

Poindexter, S.; Morgan, N. D.; Kochanek, C. S.

doi:10.1086/524190

Cited by 145 publications

(182 citation statements)

References 28 publications

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“…These values agree with the radii obtained for the lensed quasars HE1104−1805 and Q2237+0305 on the basis of their photometric variability due to microlensing (e.g. Poindexter et al 2008;Eigenbrod et al 2008;Anguita et al 2008b).…”

Section: Microlensing Of the Continuum Sourcesupporting

confidence: 89%

Microlensing in H1413+117: disentangling line profile emission and absorption in a broad absorption line quasar

Hutsemékers

Borguet

Sluse

et al. 2010

A&A

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On the basis of 16 years of spectroscopic observations of the four components of the gravitationally lensed broad absorption line (BAL) quasar H1413+117, covering the ultraviolet to visible rest-frame spectral range, we analyze the spectral differences observed in the P Cygni-type line profiles and have used the microlensing effect to derive new clues to the BAL profile formation. We first find that the absorption gradually decreases with time in all components and that this intrinsic variation is accompanied by a decrease in the intensity of the emission. We confirm that the spectral differences observed in component D can be attributed to a microlensing effect lasting at least a decade. We show that microlensing magnifies the continuum source in image D, leaving the emission line region essentially unaffected. We interpret the differences seen in the absorption profiles of component D as the result of an emission line superimposed onto a nearly black absorption profile. We also find that the continuum source and a part of the broad emission line region are likely de-magnified in component C, while components A and B are not affected by microlensing. Differential dust extinction is measured between the A and B lines of sight. We show that microlensing of the continuum source in component D has a chromatic dependence compatible with the thermal continuum emission of a standard Shakura-Sunyaev accretion disk. Using a simple decomposition method to separate the part of the line profiles affected by microlensing and coming from a compact region from the part unaffected by this effect and coming from a larger region, we disentangle the true absorption line profiles from the true emission line profiles. The extracted emission line profiles appear double-peaked, suggesting that the emission is occulted by a strong absorber, narrower in velocity than the full absorption profile, and emitting little by itself. We propose that the outflow around H1413+117 is constituted by a high-velocity polar flow and a denser, lower velocity disk seen nearly edge-on. Finally, we report on the first ground-based polarimetric measurements of the four components of H1413+117.

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Section: Microlensing Of the Continuum Sourcesupporting

confidence: 89%

Microlensing in H1413+117: disentangling line profile emission and absorption in a broad absorption line quasar

Hutsemékers

Borguet

Sluse

et al. 2010

A&A

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“…The study of the disk temperature profile is more complicated because multi-wavelength observations are needed to detect chromatic microlensing (Anguita et al 2008;Bate et al 2008;Eigenbrod et al 2008;Poindexter et al 2008;Floyd et al 2009;Blackburne et al 2011Blackburne et al , 2015Mediavilla et al 2011b;Muñoz et al 2011;Motta et al 2012;Rojas et al 2014). In this case, it also becomes more important to separate the contributions from strong emission lines.…”

Section: Introductionmentioning

confidence: 99%

Structure of the Accretion Disk in the Lensed Quasar Q2237+0305 From Multi-Epoch and Multi-Wavelength Narrowband Photometry

Muñoz

Vives-Arias

Mosquera

et al. 2016

ApJ

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We present estimates for the size and the logarithmic slope of the disk temperature profile of the lensed quasar Q2237+0305, independent of the component velocities. These estimates are based on six epochs of multiwavelength narrowband images from the Nordic Optical Telescope. For each pair of lensed images and each photometric band, we determine the microlensing amplitude and chromaticity using pre-existing mid-IR photometry to define the baseline for no microlensing magnification. A statistical comparison of the combined microlensing data (6 epochs×5 narrow bands×6 image pairs) with simulations based on microlensing magnification maps gives Bayesian estimates for the half-light radius oflt-day, and p=0.95±0.33 for the exponent of the logarithmic temperature profile µ -T R p 1 . This size estimate is in good agreement with most recent studies. Other works based on the study of single microlensing events predict smaller sizes, but could be statistically biased by focusing on high-magnification events.

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“…There is the series of papers where the semi-empirical method of determining of the accretion disk scale R λ has been developed (see Kochanek et al 2006;Poindexter et al 2008;Morgan et al 2007Morgan et al , 2008. The authors used microlensing variability observed for gravitationally lensed quasars to find the accretion disk size and the observed (or rest-frame) wavelength relation.…”

Section: Some Results From Accretion Disk Modelsmentioning

confidence: 99%

“…Now let us estimate the value of R λ for the model of a standard accretion disk using the observational data of NGC 4258. The spatial structure of standard accretion disk have been calculated by Poindexter et al (2008). The size scaling is determined by Eq.…”

Section: Estimates Of the Magnetic Field At The Horizon Of The Black mentioning

confidence: 99%

Magnetic fields of AGNs and standard accretion disk model: testing by optical polarimetry

Силантьев

Piotrovich

Gnedin

et al. 2009

A&A

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We have developed the method that allows us to estimate the magnetic field strength at the horizon of a supermassive black hole (SMBH) through the observed polarization of optical emission of the accreting disk surrounding SMBH. The known asymptotic formulae for the Stokes parameters of outgoing radiation are azimuthal averaged, which corresponds to an observation of the disk as a whole. We consider two models of the embedding 3D-magnetic field, the regular field, and the regular field with an additional chaotic (turbulent) component. It is shown that the second model is preferable for estimating the magnetic field in NGC 4258. For estimations we used the standard accretion disk model assuming that the same power-law dependence of the magnetic field follows from the range of the optical emission down to the horizon. The observed optical polarization from NGC 4258 allowed us to find the values 10 3 −10 4 Gauss at the horizon, depending on the particular choice of the model parameters. We also discuss the wavelength dependencies of the light polarization, and possibly applying them for a more realistic choice of accretion disk parameters.

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The Spatial Structure of an Accretion Disk

Cited by 145 publications

References 28 publications

Microlensing in H1413+117: disentangling line profile emission and absorption in a broad absorption line quasar

Microlensing in H1413+117: disentangling line profile emission and absorption in a broad absorption line quasar

Structure of the Accretion Disk in the Lensed Quasar Q2237+0305 From Multi-Epoch and Multi-Wavelength Narrowband Photometry

Magnetic fields of AGNs and standard accretion disk model: testing by optical polarimetry

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