Multiwavelength campaign on Mrk 509

XI. Reverberation of the Fe Kα line

¹ School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ, UK
e-mail: ponti@iasfbo.inaf.it
² INAF – IASF Bologna, via Gobetti 101, 40129 Bologna, Italy
³ SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
⁴ Dipartimento di Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
⁵ Sterrenkundig Instituut, Universiteit Utrecht, PO Box 80000, 3508 TA Utrecht, The Netherlands
⁶ Centro de Astrobiología (CSIC-INTA), Dep. de Astrofísica, LAEFF, PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
⁷ UJF-Grenoble 1 / CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, 38041 Grenoble, France
⁸ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁹ Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
¹⁰ Instituto de Astronomía, Universidad Católica del Norte, Avenida Angamos 0610, Casilla 1280, Antofagasta, Chile
¹¹ Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
¹² Department of Physics, Virginia Tech, Blacksburg, VA 24061, USA
¹³ Department of Physics, Technion-Israel Institute of Technology, 32000 Haifa, Israel
¹⁴ Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK
¹⁵ Centrum Astronomiczne im. M. Kopernika, Rabiańska 8, 87-100 Toruń, Poland
¹⁶ ISDC Data Centre for Astrophysics, Astronomical Observatory of the University of Geneva, 16 ch. d’Ecogia, 1290 Versoix, Switzerland
¹⁷ Department of Astronomy and CRESST, University of Maryland, College Park, MD 20742, USA
¹⁸ X-ray Astrophysics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD, 20771, USA

Received: 20 April 2012
Accepted: 25 June 2012

Abstract

Context. We report on a detailed study of the Fe K emission/absorption complex in the nearby, bright Seyfert 1 galaxy Mrk 509. The study is part of an extensive XMM-Newton monitoring consisting of 10 pointings (~60 ks each) about once every 4 days, and includes a reanalysis of previous XMM-Newton and Chandra observations.

Aims. We aim at understanding the origin and location of the Fe K emission and absorption regions.

Methods. We combine the results of time-resolved spectral analysis on both short and long time-scales including model-independent rms spectra.

Results. Mrk 509 shows a clear (EW = 58 ± 4 eV) neutral Fe Kα emission line that can be decomposed into a narrow (σ = 0.027 keV) component (found in the Chandra HETG data) plus a resolved (σ = 0.22 keV) component. We find the first successful measurement of a linear correlation between the intensity of the resolved line component and the 3–10 keV flux variations on time scales of years down to a few days. The Fe Kα reverberates the hard X-ray continuum without any measurable lag, suggesting that the region producing the resolved Fe Kα component is located within a few light days to a week (r ≲ 10³r_g) from the black hole (BH). The lack of a redshifted wing in the line poses a lower limit of  ≥40 r_g for its distance from the BH. The Fe Kα could thus be emitted from the inner regions of the BLR, i.e. within the  ~80 light days indicated by the Hβ line measurements. In addition to these two neutral Fe Kα components, we confirm the detection of weak (EW ~ 8–20 eV) ionised Fe K emission. This ionised line can be modelled with either a blend of two narrow Fe xxv and Fe xxvi emission lines (possibly produced by scattering from distant material) or with a single relativistic line produced, in an ionised disc, down to a few r_g from the BH. In the latter interpretation, the presence of an ionised standard α-disc, down to a few r_g, is consistent with the source high Eddington ratio. Finally, we observe a weakening/disappearing of the medium- and high-velocity high-ionisation Fe K wind features found in previous XMM-Newton observations.

Conclusions. This campaign has made the first reverberation measurement of the resolved component of the Fe Kα line possible, from which we can infer a location for the bulk of its emission at a distance of r ~ 40–1000 r_g from the BH.