The XMM-Newton View of the Nucleus of NGC 4261

Abstract

We present the first results from an XMM-Newton observation of the Fanaroff-Riley type I galaxy NGC 4261, which harbors a supermassive black hole and a low-ionization nuclear emission-line region. Here we focus on the X-ray properties of the nucleus, using the European Photon Imaging Camera pn data. The 0.6-10 keV continuum in best fitted by a thermal component with kT~0.7 keV, plus a power law with photon index Γ~1.4, absorbed by a column density N_H~4×10²² cm^-2. An unresolved Fe K emission line with EW~280 eV is detected at ~7 keV. We also detect, for the first time, short-term flux variability from the nucleus, on a timescale of 3-5 ks. The short-term variations rule out an advection-dominated accretion flow as the only production mechanism of the X-ray continuum. Instead, we argue that the inner jet contributes to the emission in the X-ray band.