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Anatomy of the AGN in NGC 5548 I. A global model for the broadband spectral energy distribution

Mehdipour, M. and Harrison, F. A. and Walton, D. J. (2015) Anatomy of the AGN in NGC 5548 I. A global model for the broadband spectral energy distribution. Astronomy and Astrophysics, 575 . Art. No. A22. ISSN 0004-6361. doi:10.1051/0004-6361/201425373.

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An extensive multi-satellite campaign on NGC 5548 has revealed this archetypal Seyfert-1 galaxy to be in an exceptional state of persistent heavy absorption. Our observations taken in 2013–2014 with XMM-Newton, Swift, NuSTAR, INTEGRAL, Chandra, HST and two ground-based observatories have together enabled us to establish that this unexpected phenomenon is caused by an outflowing stream of weakly ionised gas (called the obscurer), extending from the vicinity of the accretion disk to the broad-line region. In this work we present the details of our campaign and the data obtained by all the observatories. We determine the spectral energy distribution of NGC 5548 from near-infrared to hard X-rays by establishing the contribution of various emission and absorption processes taking place along our line of sight towards the central engine. We thus uncover the intrinsic emission and produce a broadband continuum model for both obscured (average summer 2013 data) and unobscured (<2011) epochs of NGC 5548. Our results suggest that the intrinsic NIR/optical/UV continuum is a single Comptonised component with its higher energy tail creating the “soft X-ray excess”. This component is compatible with emission from a warm, optically-thick corona as part of the inner accretion disk. We then investigate the effects of the continuum on the ionisation balance and thermal stability of photoionised gas for unobscured and obscured epochs.

Item Type:Article
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URLURL TypeDescription Paper
Harrison, F. A.0000-0003-2992-8024
Walton, D. J.0000-0001-5819-3552
Additional Information:© 2015 ESO. Received: 20 November 2014. Accepted: 18 December 2014. Published online 13 February 2015. This work is based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and the USA (NASA). This research has made use of data obtained with the NuSTAR mission, a project led by the California Institute of Technology (Caltech), managed by the Jet Propulsion Laboratory (JPL) and funded by NASA. It is also based on observations with INTEGRAL, an ESA project with instrument and science data centre funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, Spain), Czech Republic, and Poland and with the participation of Russia and the USA. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. We thank the Chandra team for allocating the LETGS triggered observations. We thank the International Space Science Institute (ISSI) in Bern for their support and hospitality. SRON is supported financially by NWO, the Netherlands Organization for Scientific Research. This publication is supported as a project of the Nordrhein-Westfälische Akademie der Wissenschaften und der Künste in the framework of the academy program by the Federal Republic of Germany and the state Nordrhein-Westfalen. M.M. acknowledges support from NWO and the UK STFC. This work was supported by NASA through grants for HST program number 13184 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. M.C. acknowledges financial support from contracts ASI/INAF n.I/037/12/0 and PRIN INAF 2011 and 2012. P.-O.P. acknowledges financial support from the CNES and from the CNRS/PICS. K.C.S. acknowledges financial support from the Fondo Fortalecimiento de la Productividad Científica VRIDT 2013. E.B. is supported by grants from the ISF, MoST (1163/10), and the iCORE program. S.B., G.M. and A.D.R. acknowledge INAF/PICS financial support. G.M. and F.U. acknowledge financial support from the Italian Space Agency under grant ASI/INAF I/037/12/0-011/13. B.M.P. acknowledges support from the US NSF through grant AST-1008882. G.P. acknowledges support via an EU Marie Curie Intra-European fellowship under contract No. FP-PEOPLE-2012-IEF-331095 and Bundesministerium für Wirtschaft und Technologie/Deutsches Zentrum für Luft- und Raumfahrt (BMWI/DLR, FKZ 50 OR 1408). F.U. acknowledges Ph.D. funding from the VINCI program of the French-Italian University. M.W. acknowledges the support of a Ph.D. studentship awarded by the UK STFC. We thank the anonymous referee for their useful suggestions and comments.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
International Space Science Institute (ISSI)UNSPECIFIED
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
Federal Republic of Germany and the state Nordrhein-WestfalenUNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Agenzia Spaziale Italiana (ASI)I/037/12/0-011/13
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Le Projet International de Coopération Scientifique (PICS)UNSPECIFIED
Fondo Fortalecimiento de la Productividad Científica VRIDT 2013UNSPECIFIED
Israel Science Foundation1163/10
Agenzia Spaziale Italiana (ASI)ASI/INAF I/037/12/0-011/13
Marie Curie FellowshipFP-PEOPLE-2012-IEF-331095
Bundesministerium für Wirtschaft und Technologie (BMWi)BMWI/DLR, FKZ 50 OR 1408
French-Italian University VINCI programUNSPECIFIED
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Deutsches Zentrum fur Luft- und Raumfahrt (DLR)UNSPECIFIED
Subject Keywords:X-rays: galaxies, galaxies: active, galaxies: Seyfert, galaxies: individual: NGC 5548, techniques: spectroscopic
Record Number:CaltechAUTHORS:20150413-101235733
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Official Citation:M. Mehdipour, J. S. Kaastra, G. A. Kriss, M. Cappi, P.-O. Petrucci, K. C. Steenbrugge, N. Arav, E. Behar, S. Bianchi, R. Boissay, G. Branduardi-Raymont, E. Costantini, J. Ebrero, L. Di Gesu, F. A. Harrison, S. Kaspi, B. De Marco, G. Matt, S. Paltani, B. M. Peterson, G. Ponti, F. Pozo Nuñez, A. De Rosa, F. Ursini, C. P. de Vries, D. J. Walton and M. Whewell A&A 575 A22 (2015) DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:56594
Deposited On:13 Apr 2015 17:54
Last Modified:10 Nov 2021 21:01

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