XMM-Newton observation of an unusual iron line in the quasar Markarian 205

¹ X-Ray Astronomy Group, Department of Physics and Astronomy, Leicester University, Leicester LE1 7RH, UK
² Max-Planck-Institut für extraterrestrische Physik, Postfach 1603, 85748 Garching, Germany
³ Service d'Astrophysique, CEA Saclay, 91191 Gif-sur-Yvette, France
⁴ Institut für Astronomie und Astrophysik - Astronomie, University of Tübingen, Waldhäuser Strasse 64, 72076 Tübingen, Germany
⁵ Istituto di Fisica Cosmica "G. Occhialini", C.N.R., Via Bassini 15, 20133 Milano, Italy

J. N. Reeves

Received: 28 September 2000
Accepted: 20 October 2000

Abstract

XMM-Newton observations of the low luminosity, radio-quiet quasar Markarian 205 have revealed a unique iron K emission line profile. In marked contrast to the broad and redshifted iron K line commonly seen in ASCA observations of Seyfert 1 galaxies, we find that a substantial amount of the line flux in Mrk 205 occurs above the neutral line energy of 6.4 keV. Furthermore, we find that the iron line emission has two distinct components, a narrow, unresolved neutral line at 6.4 keV and a broadened line centred at 6.7 keV. We suggest that the most likely origin of the 6.7 keV line is from X-ray reflection off the surface of a highly ionised accretion disk, whilst the 6.4 keV component may arise from neutral matter distant from the black hole, quite possibly in the putative molecular torus. Overall this observation underlines the potential of XMM-Newton for using the iron K line as a diagnostic of matter in the innermost regions of AGN.