Combined long and short time-scale X-ray variability of NGC 4051 with<i>RXTE</i>and<i>XMM-Newton</i>

McHardy, I. M.; Papadakis, I. E.; Uttley, P.; Page, M. J.; Mason, K. O.

doi:10.1111/j.1365-2966.2004.07376.x

Cited by 344 publications

(533 citation statements)

References 55 publications

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“…The first time-scale dependent hard lags at low frequencies were discovered by Papadakis et al (2001), with similar lags found in several other AGN (Vaughan et al 2003b;McHardy et al 2004;Markowitz et al 2007;Arévalo et al 2008a). These AGN hard lags showed a time-scale and energy dependence consistent with those seen in BHXRBs, suggesting a similar physical origin.…”

Section: Introductionmentioning

confidence: 76%

X-ray reverberation around accreting black holes

Uttley

Cackett

Fabian³

et al. 2014

Astron Astrophys Rev

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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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Section: Introductionmentioning

confidence: 76%

X-ray reverberation around accreting black holes

Uttley

Cackett

Fabian³

et al. 2014

Astron Astrophys Rev

Self Cite

461

606

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“…'Xray time lags') 1 which are routinely observed to display similar behaviour but with their frequencies and amplitudes roughly scaled inversely with black hole mass (e.g. Lawrence et al 1987;Uttley, McHardy & Papadakis 2002;Markowitz et al 2003;McHardy et al 2004;McHardy et al 2006;Arévalo et al 2008). Additionally, the rms amplitude of X-ray variability is commonly observed to scale linearly with the flux of the source (i.e.…”

Section: Introductionmentioning

confidence: 96%

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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“…For the segment 2 light curves of 3C 279, the power law PSD model is the better shape for 3/5 light curves (4.8 GHz, 22.2 GHz and 36.8 GHz) with a mean slope of −2.3 ± 0.4, indicating that the PSD slope has not changed much between segments 1 and 2. For the remaining segment 2 light curves (8 GHz, 14.5 GHz), either both models could describe the PSD shape or both may not suitably describe them which then necessitates the use of other PSD models such as the generalized bending power law (McHardy et al 2004), the damped random walk (Kelly, Bechtold, & Siemiginowska 2009;MacLeod et al 2010;Sobolewska et al 2014) or the continuous auto regressive moving average process . For the light curves of BL Lacertae, the power law PSD shape is the better model with a mean slope of −1.8 ± 0.3.…”

Section: Core Shift Effectmentioning

confidence: 99%

Core shift effect in blazars

Agarwal

Mohan

Gupta

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We studied the pc-scale core shift effect using radio light curves for three blazars, S5 0716+714, 3C 279 and BL Lacertae, which were monitored at five frequencies (ν) between 4.8 GHz and 36.8 GHz using the University of Michigan Radio Astronomical Observatory (UMRAO), the Crimean Astrophysical Observatory (CrAO), and Metsahovi Radio Observatory for over 40 years. Flares were Gaussian fitted to derive time delays between observed frequencies for each flare (∆t), peak amplitude (A), and their half width. Using A ∝ ν α we infer α in the range −16.67 to 2.41 and using ∆t ∝ ν 1/kr , we infer k r ∼ 1, employed in the context of equipartition between magnetic and kinetic energy density for parameter estimation. From the estimated core position offset (Ω rν ) and the core radius (r core ), we infer that opacity model may not be valid in all cases. The mean magnetic field strength at 1 pc (B 1 ) and at the core (B core ), are in agreement with previous estimates. We apply the magnetically arrested disk model to estimate black hole spins in the range 0.15 − 0.9 for these blazars, indicating that the model is consistent with expected accretion mode in such sources. The power law shaped power spectral density has slopes −1.3 to −2.3 and is interpreted in terms of multiple shocks or magnetic instabilities.

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Combined long and short time-scale X-ray variability of NGC 4051 withRXTEandXMM-Newton

Cited by 344 publications

References 55 publications

X-ray reverberation around accreting black holes

X-ray reverberation around accreting black holes

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

Core shift effect in blazars

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