Anatomy of the AGN in NGC 5548

Mehdipour, M.; Kaastra, J. S.; Kriss, G. A.; Cappi, M.; Petrucci, P.-O.; Steenbrugge, K. C.; Arav, Nahum; Behar, E.; Bianchi, S.; Boissay, R.; Branduardi‐Raymont, G.; Costantini, E.; Ebrero, J.; Gesu, Laura Di; Harrison, Fiona A.; Kaspi, S.; Marco, Barbara De; Matt, Giorgio; Paltani, S.; Peterson, B. M.; Ponti, G.; Núñez, F. Pozo; Rosa, A. De; Ursini, F.; Vries, C. P. de; Walton, D. J.; Whewell, M.

doi:10.1051/0004-6361/201425373

Cited by 171 publications

(260 citation statements)

References 82 publications

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“…Perhaps such material is added to the central part which increases, periodically, the X-ray emission from the disk corona which, in turn, illuminates the central disk thus boosting the optical light emitted from its surface. X-ray illumination is known to be very important in NGC5548 (Kaastra et al 2014;Mehdipour et al 2015Mehdipour et al , 2016, thus such possibilities cannot be excluded. A detailed discussion of such a scenario is beyond the scope of the present paper.…”

Section: Tidal Disruption Eventsmentioning

confidence: 99%

Evidence for Periodicity in 43 Year-Long Monitoring of NGC 5548

Bon¹,

Zucker²,

Netzer³

et al. 2016

ApJS

113

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We present an analysis of 43 years (1972 to 2015) of spectroscopic observations of the Seyfert 1 galaxy NGC 5548. This includes 12 years of new unpublished observations (2003 to 2015). We compiled about 1600 Hβ spectra and analyzed the long-term spectral variations of the 5100Å continuum and the Hβ line. Our analysis is based on standard procedures, including the LombScargle method, which is known to be rather limited to such heterogeneous data sets, and a new method developed specifically for this project that is more robust and reveals a -2 -∼5700 day periodicity in the continuum light curve, the Hβ light curve, and the radial velocity curve of the red wing of the Hβ line. The data are consistent with orbital motion inside the broad emission line region of the source. We discuss several possible mechanisms that can explain this periodicity, including orbiting dusty and dust-free clouds, a binary black hole system, tidal disruption events, and the effect of an orbiting star periodically passing through an accretion disk.

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Section: Tidal Disruption Eventsmentioning

confidence: 99%

Evidence for Periodicity in 43 Year-Long Monitoring of NGC 5548

Bon¹,

Zucker²,

Netzer³

et al. 2016

ApJS

113

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“…The campaign is introduced in detail in Mehdipour et al (2015;hereafter Paper I). The main results from the campaign, the simultaneous appearance of an exceptional obscuring event in the X-rays and a broad absorption line (BAL) structure in the UV, are presented in Kaastra et al (2014; hereafter Paper 0).…”

Section: Introductionmentioning

confidence: 99%

Anatomy of the AGN in NGC 5548

Cappi

Marco

Ponti

et al. 2016

A&A

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In 2013, we conducted a large multi-wavelength campaign on the archetypical Seyfert 1 galaxy NGC 5548. Unexpectedly, this usually unobscured source appeared strongly absorbed in the soft X-rays during the entire campaign, and signatures of new and strong outflows were present in the almost simultaneous UV HST/COS data. Here we carry out a comprehensive spectral analysis of all available XMM-Newton observations of NGC 5548 (precisely 14 observations from our campaign plus three from the archive, for a total of ∼763 ks) in combination with three simultaneous NuSTAR observations. We obtain a best-fit underlying continuum model composed by i) a weakly varying flat (Γ ∼ 1.5-1.7) power-law component; ii) a constant, cold reflection (FeK + continuum) component; iii) a soft excess, possibly owing to thermal Comptonization; and iv) a constant, ionized scattered emission-line dominated component. Our main findings are that, during the 2013 campaign, the first three of these components appear to be partially covered by a heavy and variable obscurer that is located along the line of sight (LOS), which is consistent with a multilayer of cold and mildly ionized gas. We characterize in detail the short timescale (mostly ∼ks-to-days) spectral variability of this new obscurer, and find it is mostly due to a combination of column density and covering factor variations, on top of intrinsic power-law (flux and slope) variations. In addition, our best-fit spectrum is left with several (but marginal) absorption features at rest-frame energies ∼6.7−6.9 keV and ∼8 keV, as well as a weak broad emission line feature redwards of the 6.4 keV emission line. These could indicate a more complex underlying model, e.g. a P-Cygni-type emission profile if we allow for a large velocity and wide-angle outflow. These findings are consistent with a picture where the obscurer represents the manifestation along the LOS of a multilayer of gas, which is also in multiphase, and which is likely outflowing at high speed, and simultaneously producing heavy obscuration and scattering in the X-rays, as well as broad absorption features in the UV.

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“…All photoionisation simulations are done with the most recent version of the CLOUDY code (Ferland et al, 2017). To accommodate broad types of ionizing SEDs in our calculations, we considered four distinct AGN types: Sy1.5 galaxy Mrk 509 (Kaastra et al, 2011), Sy1 galaxy NGC 5548 (Mehdipour et al, 2015), NLSy1 galaxy PMN J0948+0022 (D'Ammando et al, 2015), and LINER NGC 1097 (Nemmen et al, 2014), each of them obtained from currently available simultaneous multi-wavelength observations. As a result of our simulations, we derived the line emissivity radial profiles for major emission lines:[Hβ λ4861.36 Å, He II λ1640.00 Å, Mg II λ2798.0 Å, C III] λ1909.00 Å and…”

Section: Introductionmentioning

confidence: 99%

On the Intermediate Line Region in AGNs

Adhikari

Różáńska

Hryniewicz

et al. 2017

Front. Astron. Space Sci.

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In this paper we explore the intermediate line region (ILR) by using the photoionisation simulations of the gas clouds present at different radial distances from the center, corresponding to the locations from BLR out to NLR in four types of AGNs. We let for the presence of dust whenever conditions allow for dust existence. All spectral shapes are taken from the recent multi-wavelength campaigns. The cloud density decreases with distance as a power law. We found that the slope of the power law density profile does not affect the line emissivity radial profiles of major emission lines: Hβ, He II, Mg II, C III, and O III. When the density of the cloud at the sublimation radius is as high as 10 11.5 cm −3 , the ILR should clearly be seen in the observations independently of the shape of the illuminating radiation. Moreover, our result is valid for low ionization nuclear emission regions of active galaxies.

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Anatomy of the AGN in NGC 5548

Cited by 171 publications

References 82 publications

Evidence for Periodicity in 43 Year-Long Monitoring of NGC 5548

Evidence for Periodicity in 43 Year-Long Monitoring of NGC 5548

Anatomy of the AGN in NGC 5548

On the Intermediate Line Region in AGNs

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