Echo mapping of active galactic nuclei

Peterson, B. M.; Horne, K.

doi:10.1002/asna.200310207

Cited by 45 publications

(63 citation statements)

References 26 publications

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“…If this dusty ring is viewed at an intermediate angle, it can explain the lack of delay at less than 60 days and at the same time reproduce the continuous rise of the MIR flux. This was demonstrated by the similar doublehorn transfer function for an inclined ring calculated for broadline reverberation mapping study (Peterson & Horne 2004). These horns are separated by r c 2 cos q , where r is the radius of the ring and θ is the inclination angle of the ring.…”

Section: Dust Echo Of a Tde?mentioning

confidence: 57%

Discovery of a Mid-infrared Echo from the TDE Candidate in the Nucleus of ULIRG F01004−2237

Dou

Wang²,

Yan

et al. 2017

ApJL

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We present the mid-infrared (MIR) light curves (LCs) of a tidal disruption event candidate in the center of a nearby ultraluminous infrared galaxy F01004−2237 using archival WISE and NEOWISE data from 2010 to 2016. At the peak of the optical flare, F01004−2237 was IR quiescent. About three years later, its MIR fluxes have shown a steady increase, rising by 1.34 and 1.04 mag in 3.4 and 4.6 μm up to the end of 2016. The host-subtracted MIR peak luminosity is 2-3×10 44 erg s −1 . We interpret the MIR LCs as an infrared echo, i.e., dust reprocessed emission of the optical flare. Fitting the MIR LCs using our dust model, we infer a dust torus of the size of a few parsecs at some inclined angle. The derived dust temperatures range from 590-850 K, and the warm dust mass is ∼7 M e . Such a large mass implies that the dust cannot be newly formed. We also derive the UV luminosity of 4-11×10 44 erg s −1 . The inferred total IR energy is 1-2×10 52 erg, suggesting a large dust covering factor. Finally, our dust model suggests that the long tail of the optical flare could be due to dust scattering.

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Section: Dust Echo Of a Tde?mentioning

confidence: 57%

Discovery of a Mid-infrared Echo from the TDE Candidate in the Nucleus of ULIRG F01004−2237

Dou

Wang²,

Yan

et al. 2017

ApJL

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“…This result validates the use of LINMIX ERR as a reliable tool to quantify the quasar variability amplitude, and eventually its magnitude−magnitude correlation. It should be noted that the broad-band photometric light curves contain the flux variability not only of the accretion disc continuum emission but also of the broad emission lines and the Balmer continuum emission (e.g., Blandford & McKee 1982;O'Brien, Goad & Gondhalekar 1995;Baldwin et al 1995;Korista & Goad 2001;Peterson & Horne 2004;Korista & Goad 2004;Wilhite et al 2005;Czerny et al 2013;Kokubo et al 2014;Chelouche et al 2014;Hernitschek et al 2014;Edelson et al 2015). However, contamination of emission line variability only makes the scatter in magnitude−magnitude space σint(data) larger because of the reverberation nature of the emission line variability (e.g., Sakata et al 2011;Schmidt et al 2012).…”

Section: Methodsmentioning

confidence: 99%

Constraints on the temperature inhomogeneity in quasar accretion discs from the ultraviolet-optical spectral variability

Kokubo

2015

Monthly Notices of the Royal Astronomical Society

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The physical mechanisms of the quasar ultraviolet (UV)-optical variability are not well understood despite the long history of observations. Recently, Dexter & Agol presented a model of quasar UV-optical variability, which assumes large local temperature fluctuations in the quasar accretion discs. This inhomogeneous accretion disc model is claimed to describe not only the single-band variability amplitude, but also microlensing size constraints and the quasar composite spectral shape. In this work, we examine the validity of the inhomogeneous accretion disc model in the light of quasar UV-optical spectral variability by using five-band multi-epoch light curves for nearly 9 000 quasars in the Sloan Digital Sky Survey (SDSS) Stripe 82 region. By comparing the values of the intrinsic scatter σ int of the two-band magnitude−magnitude plots for the SDSS quasar light curves and for the simulated light curves, we show that Dexter & Agol's inhomogeneous accretion disc model cannot explain the tight inter-band correlation often observed in the SDSS quasar light curves. This result leads us to conclude that the local temperature fluctuations in the accretion discs are not the main driver of the several years' UV-optical variability of quasars, and consequently, that the assumption that the quasar accretion discs have large localized temperature fluctuations is not preferred from the viewpoint of the UV-optical spectral variability.

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“…This is a proven and powerful technique which allows the general structure and kinematics of the broad line region (BLR) in AGN to be constrained. The foundations and assumptions behind the technique are discussed in detail in the review of Peterson & Horne (2004), but the essence of the approach involves monitoring the response of optical broad line fluxes from the BLR to variations in the underlying (UV) continuum flux. The velocity dispersion Δ V estimated from the broad linewidths is related to the size r of the BLR as r ∝ (Δ V ) −2 .…”

Section: Introductionmentioning

confidence: 99%

Simultaneous X-ray/optical/UV snapshots of active galactic nuclei fromXMM-Newton: spectral energy distributions for the reverberation mapped sample

Vasudevan¹,

Fabian²

2009

Monthly Notices of the Royal Astronomical Society

351

287

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We employ contemporaneous optical, ultraviolet (UV) and X‐ray observations from the XMM–Newton European Photon Imaging Camera (EPIC‐pn) and Optical Monitor (OM) archives to present, for the first time, simultaneous spectral energy distributions (SEDs) for the majority of the Peterson et al. reverberation mapped sample of active galactic nuclei (AGN). The raw data were reduced using the latest pipelines and are all analysed consistently. The virial mass estimates from Peterson et al. allow us to calculate Eddington ratios λEdd for the sample using the bolometric accretion luminosities determined directly from the SEDs. We calculate hard X‐ray bolometric corrections κ2–10 keV for the sample and confirm a trend for increasing bolometric correction with Eddington ratio proposed in previous studies. Our comparison with previous work on these objects suggests that the OM bandpass may be less susceptible to intrinsic reddening than the far‐UV peak of the thermal disc spectrum in AGN, yielding larger bolometric corrections than previous work: κ2–10 keV≈ 15–30 for λEdd≲ 0.1, κ2–10 keV≈ 20–70 for 0.1 ≲λEdd≲ 0.2 and κ2–10 keV≈ 70–150 for λEdd≳ 0.2, but part of this increase could be attributed to spectral complexity preventing accurate recovery of the intrinsic luminosity in some sources. Long‐term optical–UV variability contributes a second order, but significant change to the total bolometric luminosity when comparing multiple observations for individual objects. We also consider the effect of a recently proposed correction for radiation pressure when determining black hole masses with reverberation mapping, and find that the revised mass estimates do not significantly alter the range of bolometric corrections seen but may yield a narrower distribution of Eddington ratios.

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Echo mapping of active galactic nuclei

Cited by 45 publications

References 26 publications

Discovery of a Mid-infrared Echo from the TDE Candidate in the Nucleus of ULIRG F01004−2237

Discovery of a Mid-infrared Echo from the TDE Candidate in the Nucleus of ULIRG F01004−2237

Constraints on the temperature inhomogeneity in quasar accretion discs from the ultraviolet-optical spectral variability

Simultaneous X-ray/optical/UV snapshots of active galactic nuclei fromXMM-Newton: spectral energy distributions for the reverberation mapped sample

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