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Multiwavelength observations and modeling of 1es 1959+650 in a low flux state
Aliu, E.; Archambault, S.; Arlen, T.; Aune, T.; Beilicke, M.; Benbow, W.; Bird, R.; Böttcher, M.; Bouvier, A.; Bugaev, V.; Byrum, K.; Cesarini, A.; Ciupik, L.; Collins-Hughes, E.; Connolly, M. P.; Cui, W.; Dickherber, R.; Duke, C.; Dumm, J.; Errando, M.
We report on the VERITAS observations of the high-frequency peaked BL Lac object 1ES 1959+650 in the period 2007-2011. This source is detected at TeV energies by VERITAS at 16.4 standard deviation (sigma) significance in 7.6 hr of observation in a low flux state. A multiwavelength spectral energy distribution (SED) is constructed from contemporaneous data from VERITAS, Fermi-LAT, RXTE PCA, and Swift UVOT. Swift XRT data is not included in the SED due to a lack of simultaneous observations with VERITAS. In contrast to the orphan gamma-ray flare exhibited by this source in 2002, the X-ray flux of the source is found to vary by an order of magnitude, while other energy regimes exhibit less variable emission. A quasi-equilibrium synchrotron self-Compton model with an additional external radiation field is used to describe three SEDs corresponding to the lowest, highest, and average X-ray states. The variation in the X-ray spectrum is modeled by changing the electron injection spectral index, with minor adjustments of the kinetic luminosity in electrons. This scenario produces small-scale flux variability of the order of less than or similar to 2 in the high energy (E > 1MeV) and very high energy (E > 100 GeV) gamma-ray regimes, which is corroborated by the Fermi-LAT, VERITAS, and Whipple 10 m telescope light curves.
Keyword(s): bl lacertae objects general; bl lacertae objects individual (1es 1959+650=ver j1959+651); galaxies active; gamma rays galaxies; bl-lacertae objects; swift ultraviolet/optical telescope; large-area telescope; gamma-rays; blazar 1es-1959+650; relativistic jet; source catalog; lac objects; tev-flare; radiation
Publication Date:
2018
Type: Journal article
Peer-Reviewed: Unknown
Institution: NUI Galway
Publisher(s): IOP Publishing
First Indexed: 2019-03-23 06:50:26 Last Updated: 2019-09-20 07:01:16