VERITAS detection of γ-ray flaring activity from the BL LAC object 1ES 1727+502 during bright moonlight observations
- 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, Iowa State University, Ames, IA 50011 (United States)
- Institute of Physics and Astronomy, University of Potsdam, 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)
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)
- Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States)
During moonlit nights, observations with ground-based Cherenkov telescopes at very high energies (VHEs, E>100 GeV) are constrained since the photomultiplier tubes (PMTs) in the telescope camera are extremely sensitive to the background moonlight. Observations with the VERITAS telescopes in the standard configuration are performed only with a moon illumination less than 35% of full moon. Since 2012, the VERITAS collaboration has implemented a new observing mode under bright moonlight, by either reducing the voltage applied to the PMTs (reduced-high-voltage; RHV configuration), or by utilizing UV-transparent filters. While these operating modes result in lower sensitivity and increased energy thresholds, the extension of the available observing time is useful for monitoring variable sources such as blazars and sources requiring spectral measurements at the highest energies. In this paper we report the detection of γ-ray flaring activity from the BL Lac object 1ES 1727+502 during RHV observations. This detection represents the first evidence of VHE variability from this blazar. The integral flux is (1.1±0.2)×10{sup −11} cm{sup −2} s{sup −1} above 250 GeV, which is about five times higher than the low-flux state. The detection triggered additional VERITAS observations during standard dark-time. Multiwavelength observations with the FLWO 48″ telescope, and the Swift and Fermi satellites are presented and used to produce the first spectral energy distribution (SED) of this object during γ-ray flaring activity. The SED is then fitted with a standard synchrotron-self-Compton model, placing constraints on the properties of the emitting region and of the acceleration mechanism at the origin of the relativistic particle population in the jet.
- OSTI ID:
- 22882821
- Journal Information:
- Astrophysical Journal, Vol. 808, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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