The local supergalaxy as the structured aspect of a universal background of X-rays

Local supergalaxy as structured aspect of X-ray backgroun

Cosmic rays from remnants of quasars?

Considerations of the collision losses for protons traversing the 2.7 K black body microwave radiation field have led to the conclusion that the highest energy cosmic rays, those observed at $\geq 10^{20}$ eV, must come from sources within the present epoch. In light of this constraint, it is here suggested that these particles may be accelerated near the event horizons of spinning supermassive black holes associated with presently inactive quasar remnants. The required emf is generated by the black hole induced rotation of externally supplied magnetic field lines threading the horizon. Producing the observed flux of the highest energy cosmic rays would constitute a negligible drain on the black hole dynamo. Observations with upcoming air shower arrays and space missions may lead to the identification of candidate dormant galaxies which harbor such black holes. Although the highest energy events observed so far are accounted for within the context of this scenario, a spectral upper bound at $\sim 10^{21}$ eV is expected since the acceleration to higher energies appears to be precluded, on general grounds.Comment: Mon. Not. Roy. Astr. Soc., in press. 5 pages, 1 tabl

An X-ray red-shift test for clusters of galaxies up to Z greater than or equal to 1

Correlated measurements of red-shifted iron line emission and apparent surface brightness are suggested for unambiguously defining intrinsic X-ray characteristics for clusters of galaxies up to z greater than or equal to 1. If some of the weak unidentified high galactic latitude X-ray sources are clusters at z approximately 1-3, then such correlated measurements should be feasible witin the complement of instruments aboard the HEAO-B orbiting X-ray telescope observatory. In addition, those clusters at z less than 1 would require spectral data from broader bandwidth experiments, such as the all-sky survey to be provided by the proportional counters aboard the first mission of the High Energy Astronomy Observatory (HEAO-A)

A Historical Perspective of Georgia's Economy

This report chronicles the history of Georgia's economy from the 1950s to the present and provides an outlook for the future growth areas in Georgia. FRC Report 10