X-Ray Characteristics of NGC 3516: A View Through the Complex Absorber

Turner, T. J.; Miller, L.; Kraemer, Steve; Reeves, J. N.

doi:10.1088/0004-637x/733/1/48

Cited by 52 publications

(44 citation statements)

References 63 publications

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“…Turner et al (2011) argue that the lack of reverberation lags in this source is evidence that the flux variations are not intrinsic to the source, however De Marco et al (2013) found such a lag at > 99% confidence, indicating reflection from the accretion disk and the presence of intrinsic variability. Turner et al (2002) found evidence of a relativistically broadened iron line in NGC 3516, and Markowitz et al (2008) found that this was still required after complex absorption is taken into account, and adding an additional absorbing component could not reproduce the spectral curvature.…”

Section: Mcgmentioning

confidence: 81%

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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Section: Mcgmentioning

confidence: 81%

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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“…As presented in Figure 3, we produced seven time-averaged and background-subtracted spectra, one from each epoch, and performed a simultaneous model fitting to them. Because of the presence of diffuse X-ray emissions in the host galaxy (e.g., Costantini et al 2000;George et al 2002) and the effects of variations in absorption (e.g., Turner et al 2011), we ignored energy bands lower than 2 keV, and utilized the 2-45 keV energies in each spectrum. The employed spectral model is wabs * (cutoffpl + pexmon) in XSPEC12, which is consistent with that utilized in Noda et al (2013aNoda et al ( , 2013b.…”

Section: X-ray Light Curves and Spectramentioning

confidence: 99%

X-Ray and Optical Correlation of Type I Seyfert NGC 3516 Studied With Suzaku and Japanese Ground-Based Telescopes

Noda

Minezaki

Watanabe

et al. 2016

ApJ

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From 2013 April to 2014 April, we performed X-ray and optical simultaneous monitoring of the type 1.5 Seyfert galaxy NGC3516. We employed Suzaku and five Japanese ground-based telescopes-the Pirka, Kiso Schmidt, Nayuta, MITSuME, and the Kanata telescopes. The Suzaku observations were conducted seven times with various intervals ranging from days or weeks to months, with an exposure of ∼50 ks each. The optical B-band observations not only covered those of Suzaku almost simultaneously, but also followed the source as frequently as possible. As a result, NGC3516 was found in its faint phase with a 2-10 keV flux of 0.21-2.70×10 −11 erg s. The 2-45 keV X-ray spectra were composed of a dominant variable hard power-law (PL) continuum with a photon index of ∼1.7 and a nonrelativistic reflection component with a prominent Fe-Kα emission line. Producing the B-band light curve by differential image photometry, we found that the B-band flux changed by ∼2.7×10 −11 erg s, which is comparable to the X-ray variation, and we detected a significant flux correlation between the hard PL component in X-rays and the B-band radiation, for the first time in NGC3516. By examining their correlation, we found that the X-ray flux preceded that in the B band by -+ 2.0 0.6 0.7 days (1σ error). Although this result supports the X-ray reprocessing model, the derived lag is too large to be explained by the standard view, which assumes a "lamppost"-type X-ray illuminator located near a standard accretion disk. Our results are better explained by assuming a hot accretion flow and a truncated disk.

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“…Specific examples include MGC −6−30−15 (McKernan & Yaqoob 1998), and also NGC 3516 (Turner et al 2011; in which their Figure 1 illustrates the extreme variability in the absorption profile).…”

Section: Introductionmentioning

confidence: 99%

New Insights Into the Spectral Variability and Physical Conditions of the X-Ray Absorbers in NGC 4151

Couto

Kraemer

Turner

et al. 2016

ApJ

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We investigate the relationship between the long term X-ray spectral variability in the Seyfert 1.5 galaxy NGC 4151 and its intrinsic absorption, by comparing the 2014 simultaneous ultraviolet/XRay observations taken with Hubble STIS Echelle and Chandra HETGS with archival observations from Chandra, XMM-Newton and Suzaku. The observations are divided into "high" and "low" states, with the low states showing strong and unabsorbed extended emission at energies below 2 keV. Our X-ray model consists of a broken powerlaw, neutral reflection and the two dominant absorption components identified by Kraemer et al. (2005), hereafter KRA2005, X-High and D+Ea, which are present in all epochs. The model fittings suggest that the absorbers are very stable, with the principal changes in the intrinsic absorption resulting from variations in the ionization state of the gas as the ionizing continuum varies. However, the low states show evidence of larger column densities in one or both of the absorbers. Among plausible explanations for the column increase, we discuss the possibility of an expanding/contracting X-ray corona. As suggested by KRA2005, there seem to be contributions from magnetohydrodynamic (MHD) winds to the mass outflow. Along with the ultra fast outflow absorber identified by Tombesi et al. (2010), X-High is consistent with being magnetically driven. On the other hand, it is unlikely that D+Ea is part of the MHD flow, and it is possible that it is radiatively accelerated. These results suggest that at a sufficiently large radial distance there is a break point between MHD-dominated and radiatively driven outflows.

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X-Ray Characteristics of NGC 3516: A View Through the Complex Absorber

Cited by 52 publications

References 63 publications

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

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

X-Ray and Optical Correlation of Type I Seyfert NGC 3516 Studied With Suzaku and Japanese Ground-Based Telescopes

New Insights Into the Spectral Variability and Physical Conditions of the X-Ray Absorbers in NGC 4151

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