Iron K features in the hard X-ray XMM-Newton spectrum of NGC 4151

Abstract

Recent XMM-Newton observations have measured the hard (2.5-12 keV) X-ray spectrum of the well-known Seyfert galaxy NGC 4151 with a signal-to-noise unprecedented for this source. We find that a spectral model, developed to fit previous Beppo-SAX and ASCA observations of NGC 4151, provides an excellent description of the XMM-Newton EPIC data. The results support the view that it is the level of the continuum that is the main driver of the complex spectral variability exhibited by NGC 4151. We focus on the iron K features in the NGC 4151 spectrum. There is no requirement for a relativistically broadened iron Ka line, in contrast to several earlier studies. The iron Ka line profile is well modelled by a narrow Gaussian, the intensity of which varies by ~25% on timescales of about a year. There is also a strong suggestion that the cold media present in the active nucleus of NGC 4151 have an iron abundance that is at least twice the solar value.