Upper limits from five years of blazar observations with the VERITAS Cherenkov telescopes
Abstract
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) {\gamma}-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 hours. 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 which 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 a spectroscopic distance estimate. 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 {\sigma} excess.
Keywords
Cite
@article{arxiv.1603.02410,
title = {Upper limits from five years of blazar observations with the VERITAS Cherenkov telescopes},
author = {S. Archambault and A. Archer and W. Benbow and R. Bird and J. Biteau and M. Buchovecky and J. H. Buckley and V. Bugaev and K. Byrum and M. Cerruti and X. Chen and L. Ciupik and M. P. Connolly and W. Cui and J. D. Eisch and M. Errando and A. Falcone and Q. Feng and J. P. Finley and H. Fleischhack and P. Fortin and L. Fortson and A. Furniss and G. H. Gillanders and S. Griffin and J. Grube and G. Gyuk and M. Hütten and N. Hakansson and D. Hanna and J. Holder and T. B. Humensky and C. A. Johnson and P. Kaaret and P. Kar and N. Kelley-Hoskins and M. Kertzman and D. Kieda and M. Krause and F. Krennrich and S. Kumar and M. J. Lang and G. Maier and S. McArthur and A. McCann and K. Meagher and P. Moriarty and R. Mukherjee and T. Nguyen and D. Nieto and A. O'Faoláin De Bhróithe and R. A. Ong and A. N. Otte and N. Park and J. S. Perkins and A. Pichel and M. Pohl and A. Popkow and E. Pueschel and J. Quinn and K. Ragan and P. T. Reynolds and G. T. Richards and E. Roache and A. C. Rovero and M. Santander and G. H. Sembroski and K. Shahinyan and A. W. Smith and D. Staszak and I. Telezhinsky and J. V. Tucci and J. Tyler and S. Vincent and S. P. Wakely and O. M. Weiner and A. Weinstein and D. A. Williams and B. Zitzer and M. Fumagalli and J. X. Prochaska},
journal= {arXiv preprint arXiv:1603.02410},
year = {2016}
}
Comments
22 pages; accepted for publication in The Astronomical Journal