Volume 577, May 2015
|Number of page(s)||9|
|Published online||28 April 2015|
Anatomy of the AGN in NGC 5548
III. The high-energy view with NuSTAR and INTEGRAL
Univ. Grenoble Alpes, IPAG,
2 CNRS, IPAG, 38000 Grenoble, France
3 Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
4 Department of Astronomy, University of Geneva, 16 Ch. d’Ecogia, 1290 Versoix, Switzerland
5 INAF-IASF Bologna, via Gobetti 101, 40129 Bologna, Italy
6 SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
7 Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA
8 Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109, USA
9 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
10 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
11 Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
12 Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK
13 Department of Astronomy, The Ohio State University, 140 W 18th Avenue, Columbus, OH 43210, USA
14 Center for Cosmology & AstroParticle Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210, USA
15 Instituto de Astronomia, Universidad Católica del Norte, Avenida Angamos 0610, Casilla 1280, Antofagasta, Chile
16 Department of Physics, University of Oxford, Keble Road, Oxford, OX1 3RH, UK
Received: 25 November 2014
Accepted: 12 January 2015
We describe the analysis of the seven broad-band X-ray continuum observations of the archetypal Seyfert 1 galaxy NGC 5548 that were obtained with XMM-Newton or Chandra, simultaneously with high-energy (>10 keV) observations with NuSTAR and INTEGRAL. These data were obtained as part of a multiwavelength campaign undertaken from the summer of 2013 till early 2014. We find evidence of a high-energy cut-off in at least one observation, which we attribute to thermal Comptonization, and a constant reflected component that is likely due to neutral material at least a few light months away from the continuum source. We confirm the presence of strong, partial covering X-ray absorption as the explanation for the sharp decrease in flux through the soft X-ray band. The obscurers appear to be variable in column density and covering fraction on time scales as short as weeks. A fit of the average spectrum over the range 0.3–400 keV with a realistic Comptonization model indicates the presence of a hot corona with a temperature of 40+40-10 keV and an optical depth of 2.7+0.7-1.2 if a spherical geometry is assumed.
Key words: galaxies: active / galaxies: Seyfert / X-rays: galaxies
© ESO, 2015
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