Modeling time delays in the X-ray spectrum of the Seyfert galaxy MCG-6-30-15

¹ Astronomical Institute of the Academy of Sciences, Boční II 1401, 14131 Prague, Czech Republic
² Observatoire de Paris, Section de Meudon, LUTH, 5 place Jules Janssen, 92195 Meudon Cedex, France
³ Copernicus Astronomical Center, Bartycka 18, 00–716 Warsaw, Poland
⁴ Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40127 Bologna, Italy
⁵ INAF–IASF Bologna, via Gobetti 101, 40129, Bologna, Italy

Received: 20 July 2006
Accepted: 12 February 2007

Abstract

Aims.We propose a reflection model of the time delays detected during an exceptionally bright, single flare in MCG-6-30-15. We consider a scenario in which the delays of the hard X-rays with respect to the soft X-rays are caused by the presence of the delayed reflection component.

Methods.We employ a model of the flare, which is accompanied by reprocessed emission. We consider two geometries/thermal states of the reprocessing medium: a partially ionized accretion disk surface and a distribution of magnetically confined, cold blobs.

Results.The reprocessing by cold blobs predicts positive time delays and a saturation in the time delay – energy relation, which is likely present in the data. The model requires a strong reflection component and relies on the apparent pivoting of the combined primary and reflected spectrum. The reflection by the ionized disk surface does not reproduce the observed delays. We discuss the relation between the two reflection scenarios and argue that they are both present in MCG-6-30-15.