ARossi X‐Ray Timing ExplorerStudy of M87 and the Core of the Virgo Cluster

We present hard X-ray observations of the nearby radio galaxy M87 and thecore of the Virgo cluster using the Rossi X-ray Timing Explorer. These are thefirst hard X-ray observations of M87 not affected by contamination from thenearby Seyfert 2 galaxy NGC4388. Thermal emission from Virgo's intraclustermedium is clearly detected and has a spectrum indicative of kT=2.5keV plasmawith approximately 25% cosmic abundances. No non-thermal (power-law) emissionfrom M87 is detected in the hard X-ray band, with fluctuations in the CosmicX-ray Background being the limiting factor. Combining with ROSAT data, we inferthat the X-ray spectrum of the M87 core and jet must be steep (Gamma_core>1.90$and Gamma_jet>1.75), and we discuss the implications of this result. Inparticular, these results are consistent with M87 being a mis-aligned BL-Lacobject.Comment: 8 pages, 2 postscript figures. Accepted for publication in Ap