A Rossi X-Ray Timing Explorer study of M87 and the core of the Virgo Cluster

We present hard X-ray observations of the nearby radio galaxy M87 and the c ore of the Virgo Cluster using the Rossi X-Ray Timing Explorer. These are t he first hard X-ray observations of M87 not affected by contamination from the nearby Seyfert 2 galaxy NGC 4388. Thermal emission from Virgo's intracl uster medium is clearly detected and has a spectrum indicative of kT approx imate to 2.5 keV plasma with approximately 25% cosmic abundances. No nonthe rmal (power-law:) emission from M87 is detected in the hard X-ray band, wit h fluctuations in the cosmic X-ray background being the limiting factor. Co mbining with ROSAT data, we infer that the X-ray spectrum of the M87 core a nd jet must be steep (T-core > 1.90 and Gamma(jet) > 1.75), and we discuss the implications of this result. In particular, these results are consisten t with being a misaligned BL Lac object.