Testing thermal reprocessing in active galactic nuclei accretion discs

Cackett, Edward M.; Horne, K.; Winkler, Hartmut

doi:10.1111/j.1365-2966.2007.12098.x

Cited by 282 publications

(387 citation statements)

References 56 publications

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“…The lags could then be simply interpreted as being due to the differential light-travel time between the emitting regions, with redder bands being emitted in the lower-temperature parts of the disc further away from the central X-ray source, hence short, red lags are observed. The detailed lag versus wavelength dependence (both amplitude and functional form) is consistent with this picture, assuming a standard disc temperature profile (Cackett et al 2007).…”

Section: Agnsupporting

confidence: 65%

Multi-Wavelength Variability

Uttley

Casella

2014

Space Sci Rev

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Multiwavelength variability data, combined with spectral-timing analysis techniques, provides information about the causal relationship between different physical components in accreting black holes. Using fast-timing data and long-term monitoring, we can probe the behaviour of the same components across the black hole mass scale. In this chapter we review the observational status of multiwavelength variability in accreting black holes, from black hole X-ray binaries to AGN, and consider the implications for models of accretion and ejection, primarily considering the evidence for accretion disc and jet variability in these systems. We end with a consideration of future prospects in this quickly-developing field.

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Section: Agnsupporting

confidence: 65%

Multi-Wavelength Variability

Uttley

Casella

2014

Space Sci Rev

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“…As such, large X-ray fluctuations may result in smaller-amplitude wavelength-dependent time delays where, in the case of an optically thick disc, the longer-wavelength counterparts are delayed with the expected relation: τ ∝ λ 4/3 (e.g. Cackett et al 2007). While the bulk of the observed optical/UV luminosity may be "intrinsic" (i.e.…”

Section: Optical/uv Monitoringmentioning

confidence: 99%

“…If the regions responsible for X-ray/UV emission are modulated by the local accretion rate, one may expect their variations to be somewhat correlated with the two favoured coupling mechanisms consisting of Compton up-scattering of UV photons to X-rays in a hot corona (e.g. Haardt & Maraschi 1991) and thermal reprocessing in the disc of primary X-rays (Guilbert & Rees 1988;Collier et al 1998;Cackett et al 2007. In both cases, the delays in the variability are governed by the light-crossing time between the two sites.…”

Section: Introductionmentioning

confidence: 99%

X-ray timing analysis of the quasar PG 1211+143

Lobban

Vaughan

Pounds

et al. 2016

Mon. Not. R. Astron. Soc.

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We report on a timing analysis of a new ∼630 ks XMM-Newton observation of the quasar, PG 1211+143. We find a well-defined X-ray power spectrum with a well-detected bend at ∼7 ×10 −5 Hz, consistent with the established t bend -M BH correlation for luminous, accreting black holes. We find the linear rms-flux relation commonly observed in accreting black hole systems and investigate the energy-dependence of the rms. The fractional rms is roughly constant with energy on short timescales (< 1 day; within observations) whereas there is enhanced soft band variability on long timescales (between observations typically spaced by a few days). Additionally, we also report on the optical-UV variability using the OM on-board XMM-Newton and a ∼2-month-long overlapping monitoring programme with Swift. We find that, although there is little UV variability within observations (< 1 day), UV variations of a few per cent exist on time-scales of ∼days-weeks.

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“…In fact, the variations in the optical continuum on day-to-week timescales in AGN, which show short (sub-day) red-lags (e.g. Cackett et al 2007), can likely only be explained by thermal reverberation of the disc in response to the rapidly-varying central EUV/X-ray source. It is interesting to note that these time-scales of optical variability are the driving time-scales for optical line reverberation from the broad-line region.…”

Section: Black Hole X-ray Binariesmentioning

confidence: 99%

X-ray reverberation around accreting black holes

Uttley

Cackett

Fabian³

et al. 2014

Astron Astrophys Rev

461

606

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Luminous accreting stellar mass and supermassive black holes produce power-law continuum X-ray emission from a compact central corona. Reverberation time lags occur due to light travel time-delays between changes in the direct coronal emission and corresponding variations in its reflection from the accretion flow. Reverberation is detectable using light curves made in different X-ray energy bands, since the direct and reflected components have different spectral shapes. Larger, lower frequency, lags are also seen and are identified with propagation of fluctuations through the accretion flow and associated corona. We review the evidence for X-ray reverberation in active galactic nuclei and black hole X-ray binaries, showing how it can be best measured and how it may be modelled. The timescales and energy-dependence of the high frequency reverberation lags show that much of the signal is originating from very close to the black hole in some objects, within a few gravitational radii of the event horizon. We consider how these signals can be studied in the future to carry out X-ray reverberation mapping of the regions closest to black holes.

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Testing thermal reprocessing in active galactic nuclei accretion discs

Cited by 282 publications

References 56 publications

Multi-Wavelength Variability

Multi-Wavelength Variability

X-ray timing analysis of the quasar PG 1211+143

X-ray reverberation around accreting black holes

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