THE BROADBAND SPECTRAL VARIABILITY OF MCG–6-30-15 OBSERVED BY<i>NUSTAR</i>AND<i>XMM-NEWTON</i>

Marinucci, Andrea; Matt, Giorgio; Miniutti, G.; Guainazzi, M.; Parker, M. L.; Brenneman, Laura; Fabian, A. C.; Kara, Erin; Arévalo, P.; Ballantyne, D. R.; Boggs, Steven E.; Cappi, M.; Christensen, Finn Erland; Craig, William W.; Elvis, M.; Hailey, Charles J.; Harrison, Fiona A.; Reynolds, C. S.; Risaliti, G.; Stern, Daniel; Walton, D. J.; Zhang, W.

doi:10.1088/0004-637x/787/1/83

Cited by 108 publications

(119 citation statements)

References 71 publications

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“…The upper 95% level is 0.8, which is somewhat inconsistent with the results obtained by modelling the X-ray spectrum of this source, which requires a ∼ 1 (e.g. Marinucci et al 2014b). This is due to our choice of M BH during the fitting procedure.…”

Section: Model B Best-fit Resultscontrasting

confidence: 87%

Theoretical modelling of the AGN iron line vs. continuum time-lags in the lamp-post geometry

Epitropakis

Papadakis

Dovčiak

et al. 2016

A&A

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Context. Theoretical modelling of time-lags between variations in the Fe Kα emission and the X-ray continuum might shed light on the physics and geometry of the X-ray emitting region in active galaxies (AGN) and X-ray binaries. We here present the results from a systematic analysis of time-lags between variations in two energy bands (5−7 vs. 2−4 keV) for seven X-ray bright and variable AGN. Aims. We estimate time-lags as accurately as possible and fit them with theoretical models in the context of the lamp-post geometry. We also constrain the geometry of the X-ray emitting region in AGN. Methods. We used all available archival XMM-Newton data for the sources in our sample and extracted light curves in the 5−7 and 2−4 keV energy bands. We used these light curves and applied a thoroughly tested (through extensive numerical simulations) recipe to estimate time-lags that have minimal bias, approximately follow a Gaussian distribution, and have known errors. Using traditional χ 2 minimisation techniques, we then fitted the observed time-lags with two different models: a phenomenological model where the time-lags have a power-law dependence on frequency, and a physical model, using the reverberation time-lags expected in the lamppost geometry. The latter were computed assuming a point-like primary X-ray source above a black hole surrounded by a neutral and prograde accretion disc with solar iron abundance. We took all relativistic effects into account for various X-ray source heights, inclination angles, and black hole spin values. Results. Given the available data, time-lags between the two energy bands can only be reliably measured at frequencies between ∼5 × 10 −5 Hz and ∼10 −3 Hz. The power-law and reverberation time-lag models can both fit the data well in terms of formal statistical characteristics. When fitting the observed time-lags to the lamp-post reverberation scenario, we can only constrain the height of the X-ray source. The data require, or are consistent with, a small ( < ∼ 10 gravitational radii) X-ray source height. Conclusions. In principle, the 5−7 keV band, which contains most of the Fe Kα line emission, could be an ideal band for studying reverberation effects, as it is expected to be dominated by the X-ray reflection component. We here carried out the best possible analysis with XMM-Newton data. Time-lags can be reliably estimated over a relatively narrow frequency range, and their errors are rather large. Nevertheless, our results are consistent with the hypothesis of X-ray reflection from the inner accretion disc.

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Section: Model B Best-fit Resultscontrasting

confidence: 87%

Theoretical modelling of the AGN iron line vs. continuum time-lags in the lamp-post geometry

Epitropakis

Papadakis

Dovčiak

et al. 2016

A&A

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“…The list of observation IDs used in this analysis for every source is shown in Table 1 (full version available online). For three sources (NGC 1365, MCG-6-30-15 and Ark 120) we have made use of data from joint XMM-Newton and NuSTAR (Harrison et al 2013) observing campaigns (Risaliti et al 2013;Walton et al 2014;Marinucci et al 2014;Matt et al 2014). All other data is publicly available, and was downloaded from the XMM-Newton Science Archive (XSA).…”

Section: Observations Data Reduction and Analysis Methodsmentioning

confidence: 99%

Revealing the X-ray variability of AGN with principal component analysis

Parker

Fabian

Matt

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We analyse a sample of 26 active galactic nuclei with deep XMM-Newton observations, using principal component analysis (PCA) to find model independent spectra of the different variable components. In total, we identify at least 12 qualitatively different patterns of spectral variability, involving several different mechanisms, including five sources which show evidence of variable relativistic reflection (MCG-6-30-15, NGC 4051, 1H 0707-495, NGC 3516 and Mrk 766) and three which show evidence of varying partial covering neutral absorption (NGC 4395, NGC 1365, and NGC 4151). In over half of the sources studied, the variability is dominated by changes in a power law continuum, both in terms of changes in flux and power law index, which could be produced by propagating fluctuations within the corona. Simulations are used to find unique predictions for different physical models, and we then attempt to qualitatively match the results from the simulations to the behaviour observed in the real data. We are able to explain a large proportion of the variability in these sources using simple models of spectral variability, but more complex models may be needed for the remainder. We have begun the process of building up a library of different principal components, so that spectral variability in AGN can quickly be matched to physical processes. We show that PCA can be an extremely powerful tool for distinguishing different patterns of variability in AGN, and that it can be used effectively on the large amounts of high-quality archival data available from the current generation of X-ray telescopes.

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“…We ignored the 1.8−2.5 keV band in order to avoid the effects of instrumental features on the broad-band energy spectrum (see e.g. Matt et al 2014;Marinucci et al 2014).…”

Section: Spectral Analysismentioning

confidence: 99%

Energy-dependent variability of the bare Seyfert 1 galaxy Ark 120

Mallick

Dewangan

McHardy

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present results from a detailed spectral-timing analysis of a long ∼ 486 ks XMM-Newton observation of the bare Seyfert 1 galaxy Ark 120 which showed alternating diminution and increment in the 0.3−10 keV X-ray flux over four consecutive orbits in 2014. We study the energy-dependent variability of Ark 120 through broad-band X-ray spectroscopy, fractional root-mean-squared (rms) spectral modelling, hardness−intensity diagram and flux−flux analysis. The X-ray (0.3−10 keV) spectra are well fitted by a thermally Comptonized primary continuum with two (blurred and distant) reflection components and an optically thick, warm Comptonization component for the soft X-ray excess emission below ∼ 2 keV. During the first and third observations, the fractional X-ray variability amplitude decreases with energy while for second and fourth observations, X-ray variability spectra are found to be inverted-crescent and crescent shaped respectively. The rms variability spectra are well modelled by two constant reflection components, a soft excess component with variable luminosity and a variable intrinsic continuum with the normalization and spectral slope being correlated. The spectral softening of the source with both the soft excess and UV luminosities favour Comptonization models where the soft excess and primary X-ray emission are produced through Compton up-scattering of the UV and UV/soft X-ray seed photons in the putative warm and hot coronae, respectively. Our analyses imply that the observed energy-dependent variability of Ark 120 is most likely due to variations in the spectral shape and luminosity of the hot corona and to variations in the luminosity of the warm corona, both of which are driven by variations in the seed photon flux.

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THE BROADBAND SPECTRAL VARIABILITY OF MCG–6-30-15 OBSERVED BYNUSTARANDXMM-NEWTON

Cited by 108 publications

References 71 publications

Theoretical modelling of the AGN iron line vs. continuum time-lags in the lamp-post geometry

Theoretical modelling of the AGN iron line vs. continuum time-lags in the lamp-post geometry

Revealing the X-ray variability of AGN with principal component analysis

Energy-dependent variability of the bare Seyfert 1 galaxy Ark 120

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