The Application of Two Dimensional Imaging to Very-High-Energy Gamma-ray Astronomy
PI: Dr. Wystan Benbow; Smithsonian Astrophysical Observatory
Abstract:
VERITAS is currently the most-sensitive VHE (E >100 GeV) gamma-ray observatory in the world. Located at the F.L. Whipple Observatory, in southern Arizona, it began full-scale operations in September 2007. Approximately 100 scientists( from 20 institutions in 4 countries are members of the VERITAS collaboration. The U.S. Department of Energy (DOE) Office of Science contributed to the development of VERITAS and funded ~42% of its $17.6 million construction cost. VERITAS was upgraded in 2012, at a cost of $2.2 million, resulting in a doubling of its sensitivity. This proposal requests from the DOE a portion of the ~$3.66 million necessary for the maintenance and the routine operation of both the VERITAS telescopes and the array facility from 2016 -2019. During this period, a five-year observing program, designed to generate the project’s legacy results, will be completed. The program addresses themes in: Particle Physics and Fundamental Laws, Black Holes, Cosmology, and Galactic Pevatrons / Tevatrons. The program also heavily leverages strong synergies with limited-lifetime U.S. facilities with no near term successor.
VERITAS is one of two US facilities for ground-based gamma-ray astronomy, and as the world’s most sensitive, it clearly provides cutting-edge research opportunities. A 2014 review stated “VERITAS is clearly an invaluable scientific facility….” VERITAS seeks to both identify new sources of VHE gamma rays, and to perform in-depth studies of the known sources to better understand their underlying fundamental processes. Since VHE gamma-raysources emit radiation over ~20 orders of magnitude in energy, these studies often involve collaboration with major experiments a lower energies. The primary targets of VERITAS Galactic observations are supernova remnants, pulsars, binary systems, and known VHE sources whose (likely Galactic) classification is unknown. The extragalactic targets observed by VERITAS include active galactic nuclei, radio galaxies, starburst galaxies, galaxy clusters, globular clusters and gamma-ray bursts. The results of these astrophysical studies often have broad implications beyond the physics of the objects themselves, addressing issues in fundamental physics (e.g., Lorentz-invariance violation), cosmology (e.g., the density of extragalactic background light and the strength of the intergalactic magnetic field), and the origin of cosmic rays.In addition to its astrophysics programs, VERITAS is used to observe Local Group galaxies, the Galactic Center and dwarf spheroidal galaxies as part of an intense program focused on the indirect detection of cold dark matter (DM). As the world’s premier VHE detector, VERITAS will continue to make the most-sensitive searches for DM in the mass region above 200 GeV. The detector will probe the DM particle mass and constrain the DM annihilation cross section within an order of magnitude of generic predictions, and strongly constrain DM scenarios with Sommerfeld or astrophysical boosts. At minimum our current limits will improve by an order of magnitude, and only a modest astrophysical boost is needed for detection.
After eight years of operation, the experiment is well-understood: array observations are routine, all maintenance / repair is handled quickly by a dedicated and experienced staff. All promised performance metrics of the experiment are achieved or surpassed, and the project has operated below its annual budget, ~6% of its upgraded construction cost, throughout its lifetime. Results from the VERITAS science programs include the detections of 55 astrophysical sources of VHE gamma rays (~170 are known). Seventy-four VERITAS articles are published in, or submitted to, refereed journals, and another ~50 journal articles are in preparation. Other output includes the publication of over 300 conference proceedings and more than40 PhD theses. Continued operation of VERITAS has guaranteed scientific return, and will ensure that the community-planned legacy results for the project can be generated.
Continued operation of VERITAS will also sustain the considerable broader impact of VERITAS in the community. The collaborationcontinues to attract new researchers:~40% of our members are PhD students and another ~20% have not yet earned their first faculty position. Women make up ~20% of the collaboration, including the heads of four research groups and the two largest science working groups. Numerous ethnic minorities are also represented. The collaboration and the FLWO Visitor’s Center coordinate many ongoing activities, websites and public displays to promote VERITAS science to the public, other educators, museum professionals and the wider community. VERITAS Project Office scientists also make an effort to provide education and public outreach experiences relevant to VERITAS in the form of multimedia products, public presentations and other low-cost activities; examples include classroom visits, a public lecture series, "star parties",and tours of the experiment.