UPPER LIMITS FROM FIVE YEARS OF BLAZAR OBSERVATIONS WITH THE VERITAS CHERENKOV TELESCOPES
- Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada)
- Department of Physics, Washington University, St. Louis, MO 63130 (United States)
- Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States)
- School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)
- Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States)
- Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
- Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)
- Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam-Golm (Germany)
- Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States)
- School of Physics, National University of Ireland Galway, University Road, Galway (Ireland)
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907 (United States)
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States)
- Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States)
- Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States)
Between the beginning of its full-scale scientific operations in 2007 and 2012, the VERITAS Cherenkov telescope array observed more than 130 blazars; of these, 26 were detected as very-high-energy (VHE; E > 100 GeV) γ -ray sources. In this work, we present the analysis results of a sample of 114 undetected objects. The observations constitute a total live-time of ∼570 hr. The sample includes several unidentified Fermi -Large Area Telescope (LAT) sources (located at high Galactic latitude) as well as all the sources from the second Fermi -LAT catalog that are contained within the field of view of the VERITAS observations. We have also performed optical spectroscopy measurements in order to estimate the redshift of some of these blazars that do not have spectroscopic distance estimates. We present new optical spectra from the Kast instrument on the Shane telescope at the Lick observatory for 18 blazars included in this work, which allowed for the successful measurement or constraint on the redshift of four of them. For each of the blazars included in our sample, we provide the flux upper limit in the VERITAS energy band. We also study the properties of the significance distributions and we present the result of a stacked analysis of the data set, which shows a 4 σ excess.
- OSTI ID:
- 22663028
- Journal Information:
- Astronomical Journal (Online), Vol. 151, Issue 6; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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