Bulletin of the American Physical Society
2008 APS April Meeting and HEDP/HEDLA Meeting
Volume 53, Number 5
Friday–Tuesday, April 11–15, 2008; St. Louis, Missouri
Session M8: Future Gamma Ray and X-Ray Astronomy Projects |
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Sponsoring Units: DAP Chair: Neil Gehrels, NASA/GSFC Room: Hyatt Regency St. Louis Riverfront (formerly Adam's Mark Hotel), Promenade A |
Sunday, April 13, 2008 3:30PM - 3:42PM |
M8.00001: White Paper on the Status and Future of Ground-based Gamma-ray Astronomy - Overview V. Vassiliev In recent years, very high-energy (VHE) gamma-ray astronomy has attracted the attention of the wider scientific community due to a number of important astrophysical discoveries made by the newly constructed ground-based gamma-ray observatories H.E.S.S, VERITAS, MAGIC, and Milagro. Among the most important findings is the discovery of a new, enigmatic population of VHE gamma-ray sources in the Milky Way. To date, some 70 TeV sources have been detected and the high discovery rate is expected to be maintained in the forthcoming years, due to the ongoing operation and upgrades of ground-based gamma-ray observatories and the long anticipated launch of the space-based gamma-ray telescope, GLAST. The continuation of these achievements into the next decade will require a new generation of observatories. In view of the long lead time for developing and installing new instruments, the Division of Astrophysics of the American Physical Society has requested the preparation of a White Paper on the status and future of ground-based gamma-ray astronomy to define the science goals of a future observatory operating at energies above 10 GeV, to determine the performance specifications, and to identify the areas requiring technology development. We outline the history and the purposes of the White Paper and report on its findings, which are based on the numerous contributions from US and international scientists. [Preview Abstract] |
Sunday, April 13, 2008 3:42PM - 3:54PM |
M8.00002: The Advanced Gamma-ray Imaging System (AGIS) James Buckley We describe a concept for a $\sim$km$^2$ ground-based gamma-ray experiment (AGIS) comprised of an array of $\sim$100 imaging atmospheric Cherenkov telescopes achieving a sensitivity an order of magnitude better than the current generation of space or ground-based instruments in the energy range of 40~GeV to $\sim$100~TeV. We present the scientific drivers for AGIS including the prospects for contributions to understanding extragalactic sources such as nearby galaxies, active galaxies, galaxy clusters and GRB; galactic sources such as X-ray binaries, supernova remnants, and pulsar wind nebulae; as well as probes of fundamental physics including indirectly detecting dark matter and probing TeV-scale physics. With the current generation of atmospheric Cherenkov telescope arrays, TeV astronomy has become well established, with the number TeV gamma-ray sources now nearing 100, including many unidentified and serendipitous sources. Improvements in the instantaneous field of view, angular resolution, effective area and energy resolution of AGIS are certain to provide great scientific returns in high energy astrophysics as well as opening up new discovery space. Here we present an overview of the ongoing design studies for AGIS including the optimization of array parameters as well as an overview of the technical drivers for the observatory. [Preview Abstract] |
Sunday, April 13, 2008 3:54PM - 4:06PM |
M8.00003: Technology Development for AGIS (Advanced Gamma-ray Imaging System). Frank Krennrich Next-generation arrays of atmospheric Cherenkov telescopes are at the conceptual planning stage and each could consist of on the order of 100 telescopes. The two currently-discussed projects AGIS in the US and CTA in Europe, have the potential to achieve an order of magnitude better sensitivity for Very High Energy (VHE) gamma-ray observations over state-to-the-art observatories. These projects require a substantial increase in scale from existing 4-telescope arrays such as VERITAS and HESS. The optimization of a large array requires exploring cost reduction and research and development for the individual elements while maximizing their performance as an array. In this context, the technology development program for AGIS will be discussed. This includes developing new optical designs, evaluating new types of photodetectors, developing fast trigger systems, integrating fast digitizers into highly-pixilated cameras, and reliability engineering of the individual components. [Preview Abstract] |
Sunday, April 13, 2008 4:06PM - 4:18PM |
M8.00004: HAWC: The Future of Wide-Field TeV Gamma-Ray Astrophysics John Pretz The High Altitude Water Cherenkov (HAWC) detector is an extensive air shower array to be constructed in Sierra Negra, Mexico. Since typical TeV gamma-ray sources are extended or variable, an all-sky instrument is necessary to perform an unbiased survey of the VHE sky. HAWC builds on the pioneering work of the Milagro experiment and represents more than order of magnitude improvement over Milagro at a moderate cost. Combining a 22000 square meter instrumented area with a 4100-meter high-altitude site, HAWC will be the most sensitive wide-field TeV gamma-ray instrument in the world. I will present the design and performance of the detector in the context of the science objectives of the collaboration. [Preview Abstract] |
Sunday, April 13, 2008 4:18PM - 4:30PM |
M8.00005: Utilizing Fractionated Space Mission Design and Small Satellites for a Next Generation Gamma Ray Burst Observatory Rashied Amini Since the discovery of Gamma Ray Bursts (GRBs) by the Vela satellite, the field of GRB astronomy has been rapidly evolving in order to explain the most catastrophic event in the universe. Missions over the last two decades have pinpointed GRBs as extragalactic sources as well as shed insight on their nature. NASA's recent SWIFT mission provides a platform for multiwavelength analysis of GRBs and their afterglow as well as transmitting GRB position data to other observatories. A future mission can compliment SWIFT's array of multiwavelength instrumentation as well as providing more rapid and precise GRB position data. A fractionated, small satellite mission can utilize the small scale of nanosatellites to rapidly slew to a GRB target and then use stereoscopic observation and long baselines to further pinpoint the GRB position. A fractionated mission design places various scientific instrumentation as the primary payload on each individual satellite, providing robust performance and a greater field of view by decentralization. Additionally, future space interferometry missions will employ formation flying and fractionated design; a fractionated, small satellite mission will provide a cost effective proof of concept while providing valuable data to the scientific community. [Preview Abstract] |
Sunday, April 13, 2008 4:30PM - 4:42PM |
M8.00006: A balloon-borne X-ray polarimeter for the study of bright astronomical sources Ramanath Cowsik Through astronomical X-ray polarimetry we can probe the extreme conditions of gravity near black holes, the intense magnetic fields near neutron stars and magnetars, the presence of very high energy particles in the shocks associated with supernova remnants, and a variety of exotic astrophysical processes such as Thomson scattering in the hot atmospheres above accretion disks and inverse Compton scattering of polarized synchrotron photons. In this paper we discuss an instrument suitable for balloon borne observations. This instrument consists of an azimuthally symmetric collimator with a trapezoidal response, which reduces the required pointing accuracies, and a position sensitive proportional counter which has external resistors distributed in series with the high voltage anode wire. This latter characteristic allows position of the scattered photon to be determined in angular steps through charge division and minimizes the on-board electronics and telemetry. A full analysis of the response of the instrument, including the competing effects of photoelectric absorption in the scattering target is presented. We show that the polarization of about a dozen astronomical x-ray sources may be probed effectively with this instrument during a long duration balloon flight from Antarctica. [Preview Abstract] |
Sunday, April 13, 2008 4:42PM - 4:54PM |
M8.00007: Pathfinder to EXIST: ProtoEXIST A.B. Garson III, B. Allen, R.G. Baker, S.D. Barthelmy, M. Burke, J. Burnham, N. Chammas, J. Collins, W.R. Cook, A. Copete, N. Gehrels, T. Gauron, J. Grindlay, F.A. Harrison, J. Hong, J. Howell, H. Krawczynski, S. Labov, B. Said, S. Sheikh Sheikh We describe the ProtoEXIST instrument, our fist-generation wide-field hard X-ray imaging (20 - 600 keV) balloon-borne telescope. The ProtoEXIST program is a pathfinder for the Energetic X-ray Imaging Survey Telescope (EXIST), a candidate for the Black Hole Finder Probe. ProtoEXIST consists of two independent coded-aperture telescopes using pixellated (2.5mm pitch) CZT detectors. The two telescopes will provide performance comparison of two shielding configurations, for optimization of the EXIST design. We report on the science goals and designs of both ProtoEXIST and EXIST and their implications for hard X-ray astronomy and astrophysics. [Preview Abstract] |
Sunday, April 13, 2008 4:54PM - 5:06PM |
M8.00008: X-Ray Astronomy Discovery Experiments* P.C. Fisher A Lockheed proposal to ``scan along the galactic equator in the direction of the galactic center {\ldots}'' $^{1}$ was made to NASA in late 1960, over a year before Giacconi's discovery of Sco X-1, in 1962.$^{2 }$ The nature of the Lockheed survey and first results were announced in 1964. Data in several publications verified the 1960 postulate that the brightest sources would lie within the galaxy and at low galactic latitude. A fourth publication summarized results.$^{3 }$ A recent listing $^{4}$ confirmed the discovery nature of the nearly fifty-year-old Lockheed proposal, and the effort's success. Data from the two concurrent experiments will be presented, and several published or just copyrighted appraisals of the two efforts will be described. \newline \newline *Work supported by NASA contracts NAS5-1174 and NASw-909, the Lockheed Independent Research Program, and several successive forms of Ruffner Associates. \newline $^{1}$P. C. Fisher, Lockheed Missiles and Space Division Document LMSD 702172, Palo Alto, (1960) \newline $^{2}$R. Giacconi \textit{et al}., Phys. Rev. Lett. \textbf{9} (1962) 439 \newline $^{3}$P. C. Fisher \textit{et al}., Astrophys. J., \textbf{151} (1968) 1. \newline $^{4}$P. C. Fisher, \textit{Who'sWho in the World}, Marquis Who's Who LLC, New Providence, NJ, 22$^{nd}$ Edition, (2005) 667-668. [Preview Abstract] |
Sunday, April 13, 2008 5:06PM - 5:18PM |
M8.00009: Recent Results from the Chandra Deep Field Surveys William Brandt The deepest Chandra surveys continue to deliver fascinating results about active galactic nuclei (AGNs), starburst \& normal galaxies, groups \& clusters, and large-scale structures in the distant X-ray universe. I will review these surveys and describe some recent results from two of them, the Chandra Deep Field-North and Extended Chandra Deep Field-South. Specifically, I will describe (1) the X-ray-to-optical properties of AGNs probed over wide luminosity and redshift ranges, (2) the obscured AGN content of distant submillimeter galaxies, and (3) the X-ray evolution of non-active late-type and early-type galaxies over the last half of cosmic time. I will also discuss some key outstanding problems and prospects for short-term and long-term advances. [Preview Abstract] |
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