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Long-term monitoring of Ark 120 with Swift

Gliozzi, M. and Papadakis, I. and Grupe, D. and Brinkmann, W. and Räth, Christoph (2017) Long-term monitoring of Ark 120 with Swift. Monthly Notices of the Royal Astronomical Society, 464, pp. 3955-3964. Oxford University Press. doi: 10.1093/mnras/stw2636. ISSN 0035-8711.

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We report the results of a six-month Swift monitoring campaign of Ark 120, a prototypical ‘bare’ Seyfert 1 galaxy. The lack of intrinsic absorption combined with the nearly contemporaneous coverage of the ultraviolet (UV) and X-ray bands makes it possible to investigate the link between the accretion disc and the putative Comptonization corona. Our observations confirm the presence of substantial temporal variability, with the X-ray characterized by large-amplitude flux changes on time scales of few days, while the variations in the UV bands are smoother and occur on time-scales of several weeks. The source also shows spectral variability with the X-ray spectrum steepening when the source is brighter. We do not detect any correlation between the UV flux and the X-ray spectral slope. A cross-correlation analysis suggests positive delays between X-rays and the UV emission, favouring a scenario of disc reprocessing. Although the strength of the correlation is moderate with a delay which is not well constrained (7.5 ± 7 d), it is nevertheless indicative of a very large disc reprocessing region, with a separation between the X-ray and the UV-emitting regions, which could be as large as 1000 rG. The Ark 120 correlation results are in agreement with those obtained in similar multiwavelength monitoring studies of active galactic nuclei (AGN). When combined together, the observations so far can be well described by a linear relation between the X-ray/UV delays and the mass of the central black hole. Within the context of the simplest scenario, where these delays correspond to light-travel times, the implied distance between the X-ray source and the optical/UV disc reprocessing region in these AGN should be of the order of many hundreds of gravitational radii.

Item URL in elib:https://elib.dlr.de/109310/
Document Type:Article
Title:Long-term monitoring of Ark 120 with Swift
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Gliozzi, M.George Mason UniversityUNSPECIFIEDUNSPECIFIED
Papadakis, I.University of CreteUNSPECIFIEDUNSPECIFIED
Grupe, D.Morehead State UniversityUNSPECIFIEDUNSPECIFIED
Brinkmann, W.Max-Planck-Institut für extraterrestrische PhysikUNSPECIFIEDUNSPECIFIED
Räth, ChristophDLR Research Group Complex PlasmasUNSPECIFIEDUNSPECIFIED
Journal or Publication Title:Monthly Notices of the Royal Astronomical Society
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 3955-3964
Publisher:Oxford University Press
Keywords:time series analysis, correlations, active galactic nuclei
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Research under Space Conditions
DLR - Research theme (Project):R - Komplexe Plasmen / Data analysis (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Materials Physics in Space > Research Group Complex Plasma
Deposited By: Räth, Christoph
Deposited On:09 Dec 2016 11:48
Last Modified:06 Sep 2019 15:17

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