Multiwavelength campaign on Mrk 509

I. Variability and spectral energy distribution

¹ SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
e-mail: j.s.kaastra@sron.nl
² Sterrenkundig Instituut, Universiteit Utrecht, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
³ UJF-Grenoble 1 / CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble 38041, France
⁴ INAF-IASF Bologna, via Gobetti 101, 40129 Bologna, Italy
⁵ Department of Physics, Virginia Tech, Blacksburg, VA 24061, USA
⁶ Department of Physics, Technion-Israel Institute of Technology, 32000 Haifa, Israel
⁷ Dipartimento di Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
⁸ Department of Astronomy, 601 Campbell Hall, University of California, Berkeley, CA 94720, USA
⁹ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
¹⁰ Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK
¹¹ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
¹² Department of Astrophysics, IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
¹³ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
¹⁴ Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
¹⁵ Centrum Astronomiczne im. M. Kopernika, Rabiańska 8, PL-87-100 Toruń, Poland
¹⁶ Université de Toulouse, UPS-OMP, IRAP, Toulouse, France
¹⁷ CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
¹⁸ ISDC Data Centre for Astrophysics, Astronomical Observatory of the University of Geneva, 16, ch. d’Ecogia, 1290 Versoix, Switzerland
¹⁹ School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ, USA
²⁰ Instituto de Astronomía, Universidad Católica del Norte, Avenida Angamos 0610, Casilla 1280, Antofagasta, Chile
²¹ Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK

Received: 11 March 2011
Accepted: 5 May 2011

Abstract

Context. Active galactic nuclei (AGN) show a wealth of interesting physical processes, some of which are poorly understood. In a broader context, they play an important role in processes that are far beyond their immediate surroundings, owing to the high emitted power.

Aims. We want to address a number of open questions, including the location and physics of the outflow from AGN, the nature of the continuum emission, the geometry and physical state of the X-ray broad emission line region, the Fe-K line complex, the metal abundances of the nucleus, and finally the interstellar medium of our own Galaxy as seen through the signatures it imprints on the X-ray and UV spectra of AGN.

Methods. We study one of the best targets for these aims, the Seyfert 1 galaxy Mrk 509 with a multiwavelength campaign using five satellites (XMM-Newton, INTEGRAL, Chandra, HST, and Swift) and two ground-based facilities (WHT and PAIRITEL). Our observations cover more than five decades in frequency, from 2 μm to 200 keV. The combination of high-resolution spectroscopy and time variability allows us to disentangle and study the different components. Our campaign covers 100 days from September to December 2009, and is centred on a simultaneous set of deep XMM-Newton and INTEGRAL observations with regular time intervals, spanning seven weeks.

Results. We obtain a continuous light curve in the X-ray and UV band, showing a strong, up to 60% flux increase in the soft X-ray band during the three weeks in the middle of our deepest monitoring campaign, and which is correlated with an enhancement of the UV flux. This allows us to study the time evolution of the continuum and the outflow. By stacking the observations, we have also obtained one of the best X-ray and UV spectra of a Seyfert galaxy ever obtained. In this paper we also study the effects of the spectral energy distribution (SED) that we obtained on the photo-ionisation equilibrium. Thanks to our broad-band coverage, uncertainties on the SED do not strongly affect the determination of this equilibrium.

Conclusions. Here we present our very successful campaign and in a series of subsequent papers we will elaborate on different aspects of our study.