A White Paper submitted to Astro2010: The Astronomy and Astrophysics Decadal Survey based in part on " The Status and Future of Ground-based TeV Gamma-ray Astronomy " , a White Paper prepared at the request of the Division of Astrophysics of the American Physical Society to summarize the status and future of ground-based γ-ray astronomy. The images above illustrate the richness available to fut...

Fellow of the Pacific Institute of Mathematical Sciences 1998-1999, Dept. of Physics and Astronomy, University of Victoria, PO Box 3055, Victoria, B.C., V8W 3P6, Canada & Astronomy Dept., University of Washington, Box 351580, Seattle WA 98195-1580, U.S.A. Electronic mail: [email protected] Electronic mail: [email protected] Dept. of Physics and Astronomy, University of Victoria, P...

Observations in the hard X-ray and gammaray energy regimes are constrained by limited sensitivity and angular resolution. Significant gains could be made if these high-energy photons could be concentrated from a large area onto a small detector element and if diffraction-limited measurements could be obtained. Furthermore, the angular resolution in the gamma-ray band would be superior to that p...

This article reviews the present status of high energy γ-ray astronomy at energies above 30 MeV. Observations in the past decade using both spaceand ground-based experiments have been primarily responsible for giving a tremendous boost to our knowledge of the high energy Universe. High energy γ-rays have been detected from a wide range of Galactic and extragalactic astrophysical sources, such a...

We present a spectral analysis of a ∼ 30 d, near-continuous observation of the Seyfert 1 galaxy NGC 7469 with RXTE. Daily integrations show strong spectral changes during the observation. Our main result is that we find the X-ray spectral index to be correlated with the UV flux. Furthermore, the broad-band X-ray photon flux is also correlated with the UV continuum. These correlations point towa...

The extremely sensitive Chandra Deep Field-North (CDF-N) pencil-beam X-ray survey is used to identify and characterize the X-ray emission from old high-latitude main sequence Galactic stars. Our principal goal is to investigate the expected long-term decay of magnetic activity of late-type stars due to the gradual spindown of stellar rotation from a magnetized stellar wind. Thirteen X-ray sourc...

The construction of large-volume detectors of high energy, greater than 1TeV, neutrinos is mainly driven by the search for extragalactic neutrino sources. The existence of such sources is implied by the observations of ultra-high-energy, greater than or equal to 1019eV, cosmic rays, the origin of which is a mystery. In this lecture, I briefly discuss the expected extragalactic neutrino signal a...