The nature of the hard X-ray power-law tail in M87

Abstract

Spatially-resolved spectroscopy of the elliptical galaxy M87 with the MECS instrument on board BeppoSAX demonstrates that the hard X-ray power-law tail, originally discovered by ASCA (Matsumoto et al 1996; Allen et al. 1999), originates in the innermost 2'. Our results are consistent with it being produced in an Accretion Dominated Flow, although a substantial jet contribution cannot be ruled out. An origin from a Seyfert-like nucleus is disfavored by our data. As a by-product of this result, we present an analysis of the thermal emission coming from the center of the Virgo cluster, which exhibits a strong positive radial temperature gradient, along with a radial decrease of the iron abundance.