Iron K and Compton hump reverberation in SWIFT J2127.4+5654 and NGC 1365 revealed by NuSTAR and XMM–Newton

Kara, Erin; Zoghbi, Abderahmen; Marinucci, Andrea; Walton, D. J.; Fabian, A. C.; Risaliti, G.; Boggs, S. E.; Christensen, Finn Erland; Fuerst, F.; Hailey, Charles J.; Harrison, Fiona A.; Matt, Giorgio; Parker, M. L.; Reynolds, C. S.; Stern, Daniel; Zhang, W. W.

doi:10.1093/mnras/stu2136

Cited by 68 publications

(80 citation statements)

References 65 publications

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“…Soft-band X-ray reverberation lags were indeed discovered with XMM-Newton in the narrow line seyfert 1 (NLS1) galaxy 1H0707-495 (Fabian et al 2009), and in other bright Seyferts (Emmanoulopoulos et al 2011;De Marco et al 2013). High-frequency iron Kα reverberation lags have also been detected in a small number of Seyfert galaxies (Zoghbi et al 2012(Zoghbi et al , 2013Kara et al 2013a,b), while similar lags have been reported for the Compton hump in a few sources as well Kara et al 2015).…”

Section: Introductionsupporting

confidence: 53%

Signatures of X-ray reverberation in the power spectra of AGN

Papadakis

Pecháček

Dovčiak

et al. 2016

A&A

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Aims. We study the effects of X-ray reprocessing in the power spectra (PSDs) of active galactic nuclei (AGNs). Methods. We compute fully relativistic disc response functions in the case of lamp-post geometry using the full observed reflection spectrum for various X-ray source heights, disc inclination, and spin values of the central black hole. Since the observed PSD is equal to the product of the intrinsic power spectrum with the transfer function (i.e. the Fourier transform of the disc response function), we are able to predict the observed PSDs in the case of X-ray illumination of the inner disc.Results. The observed PSD should show a prominent dip at high frequencies and an oscillatory behaviour with a decreasing amplitude at higher frequencies. The reverberation echo features should be more prominent in energy bands where the reflection component is more pronounced. The frequency of the dip is independent of energy, and it is mainly determined by the black hole mass and the X-ray source height. The amplitude of the dip increases with increasing black hole spin and inclination angle, as long as the height of the lamp is smaller than ∼10 gravitational radii. Conclusions. The detection of the X-ray reverberation signals in the PSDs can provide further evidence for X-ray illumination of the inner disc in AGN. Our results are largely independent of the assumed geometry of the disc-corona system, as long as it does not change with time, and the disc response function is characterized by a sharp rise, a plateau, and a decline at longer times. Irrespective of the geometry, the frequency of the main dip should decrease with increasing mean time of the response function, and the amplitude of the dip should increase with increasing reflection fraction.

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Section: Introductionsupporting

confidence: 53%

Signatures of X-ray reverberation in the power spectra of AGN

Papadakis

Pecháček

Dovčiak

et al. 2016

A&A

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“…Given that the corona emission is inhomogeneous and the scale height varies with distance in our model, the X-ray reflection emissivity is expected to differ from these simplified models. Kara et al (2015Kara et al ( , 2016 point out that the true light-travel time between the corona and the disk is longer than the observed lag measured by X-ray reverberation due to dilution effects. The direct emission from the corona, as our model reveals, unavoidably contributes a fraction to the reflection band.…”

Section: Radiation Compactness Of the Coronamentioning

confidence: 93%

“…Along this line of investigation, significant efforts have been directed toward observationally constraining the corona geometry. It is found that the coronal illumination may originate from a height less than 10R g (Detailed data analyses on the reverberation lag and deduced height of the corona can be found in Fabian et al 2009Fabian et al , 2015De Marco et al 2013;Kara et al 2013Kara et al , 2015Kara et al , 2016Reis & Miller 2013).…”

Section: Radiation Compactness Of the Coronamentioning

confidence: 99%

Centrally Concentrated X-Ray Radiation from an Extended Accreting Corona in Active Galactic Nuclei

Liu¹,

Taam²,

Qiao³

et al. 2017

ApJ

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The X-ray emission from bright active galactic nuclei (AGNs) is believed to originate in a hot corona lying above a cold, geometrically thin accretion disk. A highly concentrated corona located within ∼ 10 gravitational radii above the black hole is inferred from observations. Based on the accretion of interstellar medium/wind, a disk corona model has been proposed in which the corona is well coupled to the disk by radiation, thermal conduction, as well as by mass exchange (Liu et al. 2015;Qiao & Liu 2017). Such a model avoids artificial energy input to the corona and has been used to interpret the spectral features observed in AGN. In this work, it is shown that the bulk emission size of the corona is very small for the extended accretion flow in our model. More than 80% of the hard X-ray power is emitted from a small region confined within 10 Schwarzschild radii around a non-spinning black hole, which is expected to be even smaller accordingly for a spinning black hole. Here, the corona emission is more extended at higher Eddington ratios. The compactness parameter of the corona, l = L R σT mec 3 , is shown to be in the range of 1-33 for Eddington ratios of 0.02 -0.1. Combined with the electron temperature in the corona, this indicates that electron-positron pair production is not dominant in this regime. A positive relation between the compactness parameter and photon index is also predicted. By comparing the above model predictions with observational features, we find that the model is in agreement with observations.

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“…To the contrary, Miller et al (2010) proposed that the soft X-ray lags of 1H 0707−495 can be accounted for by reverberation due to much more distant matter. Up to now, similar soft lags are detected in a number of NLS1s (e.g., Kara et al 2015), but their origins are not fully understood. Meanwhile, Mizumoto, Ebisawa, & Sameshima (2014) (hereafter, Paper I) successfully explained the rapid variation of 1H 0707−495 by the "variable double partial covering" (VDPC) model in the 0.5-10 keV.…”

Section: Introductionmentioning

confidence: 91%

Origin of the characteristic X-ray spectral variations of IRAS 13224−3809

Yamasaki

Mizumoto

Ebisawa

et al. 2016

Publications of the Astronomical Society of Japan

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The Narrow-line Seyfert 1 galaxy (NLS1) IRAS 13224−3809 is known to exhibit significant Xray spectral variation, a sharp spectral drop at ∼ 7 keV, strong soft excess emission, and a hint of iron L-edge feature, which is very similar to the NLS1 1H 0707−495. We have proposed the "Variable Double Partial Covering (VDPC) model" to explain the energy spectra and spectral variability of 1H 0707−495 (Mizumoto, Ebisawa and Sameshima 2014, PASJ, 66, 122). In this model, the observed flux/spectral variations below 10 keV within a ∼day are primarily caused by change of the partial covering fraction of patchy clouds composed by double absorption layers in the line of sight. In this paper, we apply the VDPC model to IRAS 13224−3809. Consequently, we have found that the VDPC model can explain the observed spectral variations of IRAS 13224-3809 in the 0.5-10 keV band. In particular, we can explain the observed Root Mean Square (RMS) spectra (energy dependence of the fractional flux variation) in the entire 0.5 -10 keV band. In addition to the well-known significant drop in the iron K-band, we have found intriguing iron L-peaks in the RMS spectra when the iron L-edge is particularly deep. This feature, which is also found in 1H 0707-495, is naturally explained with the VDPC model, such that the RMS variations increase at the energies where optical depths of the partial absorbers are large. The absorbers have a larger optical depth at the iron L-edge than in the adjacent energy bands, thus a characteristic iron L-peak appears. On the other hand, just below the iron K-edge, the optical depth is the lowest and the RMS spectrum has a broad dip.

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Iron K and Compton hump reverberation in SWIFT J2127.4+5654 and NGC 1365 revealed by NuSTAR and XMM–Newton

Cited by 68 publications

References 65 publications

Signatures of X-ray reverberation in the power spectra of AGN

Signatures of X-ray reverberation in the power spectra of AGN

Centrally Concentrated X-Ray Radiation from an Extended Accreting Corona in Active Galactic Nuclei

Origin of the characteristic X-ray spectral variations of IRAS 13224−3809

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