We present the results of a joint spectral analysis of RXTE PCA, ASCA SIS, and ROSAT PSPC data of the supernova remnant SN 1006. This work represents the first attempt to model both the thermal and nonthermal X-ray emission over the entire X-ray energy band. The thermal flux is described by a nonequilibrium ionization model with an electron temperature kT e = 0.6 keV, an ionization timescale n ...

A sample of FRII radio sources in rich clusters of galaxies, both at high (z0.5) and low (z0) redshift, has been constructed to study the eeect of environment on radio sources. Comparisons are made between the properties of FRII sources in cluster and non-cluster environments, and between X-ray clusters with and without FRII sources. The principal results are the following: 1. Most low-redshift...