Multiwavelength observations of the very high energy blazar 1es 2344+514
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2011-08-23Metadata
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Acciari, V. A. Aliu, E.; Arlen, T.; Aune, T.; Beilicke, M.; Benbow, W.; Boltuch, D.; Bugaev, V.; Cannon, A.; Ciupik, L.; Cogan, P.; Colin, P.; Dickherber, R.; Falcone, A.; Fegan, S. J.; Finley, J. P.; Fortin, P.; Fortson, L. F.; Furniss, A.; Gall, D.; Gillanders, G. H.; Grube, J.; Guenette, R.; Gyuk, G.; Hanna, D.; Holder, J.; Horan, D.; Hui, C. M.; Humensky, T. B.; Imran, A.; Kaaret, P.; Karlsson, N.; Kertzman, M.; Kieda, D.; Kildea, J.; Konopelko, A.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; LeBohec, S.; Maier, G.; Moriarty, P.; Mukherjee, R.; Ong, R. A.; Otte, A. N.; Pandel, D.; Perkins, J. S.; Pichel, A.; Pohl, M.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Rose, H. J.; Schroedter, M.; Sembroski, G. H.; Smith, A. W.; Steele, D.; Swordy, S. P.; Theiling, M.; Toner, J. A.; Varlotta, A.; Vassiliev, V. V.; Vincent, S.; Wagner, R.; Wakely, S. P.; Ward, J. E.; Weekes, T. C.; Weinstein, A.; Weisgarber, T.; Williams, D. A.; Wissel, S.; Wood, M.; Zitzer, B. (2011). Multiwavelength observations of the very high energy blazar 1es 2344+514. The Astrophysical Journal 738 (2),
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Abstract
Multiwavelength observations of the high-frequency-peaked blazar 1ES 2344+514 were performed from 2007 October to 2008 January. The campaign represents the first contemporaneous data on the object at very high energy (VHE, E > 100 GeV) gamma-ray, X-ray, and UV energies. Observations with VERITAS in VHE gamma-rays yield a strong detection of 20s with 633 excess events in a total exposure of 18.1 hr live time. A strong VHE gamma-ray flare on 2007 December 7 is measured at F(> 300 GeV) = (6.76 +/- 0.62) x 10(-11) photons cm(-2) s(-1), corresponding to 48% of the Crab Nebula flux. Excluding this flaring episode, nightly variability at lower fluxes is observed with a time-averaged mean of F(> 300 GeV) = (1.06 +/- 0.09) x 10(-11) photons cm(-2) s(-1) (7.6% of the Crab Nebula flux). The differential photon spectrum between 390 GeV and 8.3 TeV for the time-averaged observations excluding 2007 December 7 is well described by a power law with a photon index of G = 2.78 +/- 0.09(stat) +/- 0.15(syst). On the flaring night of 2007 December 7 the measured VHE gamma-ray photon index was Gamma = 2.43 +/- 0.22(stat) +/- 0.15(syst). Over the full period of VERITAS observations contemporaneous X-ray and UV data were taken with Swift and RXTE. The measured 2-10 keV flux ranged by a factor of similar to 7 during the campaign. On 2007 December 8 the highest ever observed X-ray flux from 1ES 2344+514 was measured by Swift X-ray Telescope at a flux of F(2-10 keV) = (6.28 +/- 0.31) x 10(-11) erg cm(-2) s(-1). Evidence for a correlation between the X-ray flux and VHE. -ray flux on nightly timescales is indicated with a Pearson correlation coefficient of r = 0.60 +/- 0.11. Contemporaneous spectral energy distributions (SEDs) of 1ES 2344+514 are presented for two distinct flux states. A one-zone synchrotron self-Compton (SSC) model describes both SEDs using parameters consistent with previous SSC modeling of 1ES 2344+514 from non-contemporaneous observations.