Multiwavelength observations of the very high energy blazar 1ES 2344+514

V. A. Acciari, E. Aliu, T. Arlen, T. Aune, M. Beilicke, W. Benbow, D. Boltuch, V. Bugaev, A. Cannon, L. Ciupik, P. Cogan, P. Colin, R. Dickherber, A. Falcone, S. J. Fegan, J. P. Finley, P. Fortin, L. F. Fortson, A. Furniss, D. GallG. H. Gillanders, J. Grube, R. Guenette, G. Gyuk, D. Hanna, J. Holder, D. Horan, C. M. Hui, T. B. Humensky, A. Imran, P. Kaaret, N. Karlsson, M. Kertzman, D. Kieda, J. Kildea, A. Konopelko, H. Krawczynski, F. Krennrich, M. J. Lang, S. Lebohec, G. Maier, P. Moriarty, R. Mukherjee, R. A. Ong, A. N. Otte, D. Pandel, J. S. Perkins, A. Pichel, M. Pohl, J. Quinn, K. Ragan, P. T. Reynolds, H. J. Rose, M. Schroedter, G. H. Sembroski, A. W. Smith, D. Steele, S. P. Swordy, M. Theiling, J. A. Toner, A. Varlotta, V. V. Vassiliev, S. Vincent, R. Wagner, S. P. Wakely, J. E. Ward, T. C. Weekes, A. Weinstein, T. Weisgarber, D. A. Williams, S. Wissel, M. Wood, B. Zitzer

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Abstract

Multiwavelength observations of the high-frequency-peaked blazar 1ES2344+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 >100GeV) γ-ray, X-ray, and UV energies. Observations with VERITAS in VHE γ-rays yield a strong detection of 20σ with 633 excess events in a total exposure of 18.1 hr live time. A strong VHE γ-ray flare on 2007 December 7 is measured at F(>300GeV) = (6.76 0.62) × 10-11photonscm-2s-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(>300GeV) = (1.06 0.09) × 10-11photonscm-2s-1 (7.6% of the Crab Nebula flux). The differential photon spectrum between 390GeV and 8.3TeV for the time-averaged observations excluding 2007 December 7 is well described by a power law with a photon index of Γ = 2.78 0.09stat 0.15syst. On the flaring night of 2007 December 7 the measured VHE γ-ray photon index was Γ = 2.43 0.22stat 0.15 syst. Over the full period of VERITAS observations contemporaneous X-ray and UV data were taken with Swift and RXTE. The measured 2-10keV flux ranged by a factor of 7 during the campaign. On 2007 December 8 the highest ever observed X-ray flux from 1ES2344+514 was measured by Swift X-ray Telescope at a flux of F(2-10keV) = (6.28 0.31) × 10-11ergcm -2s-1. Evidence for a correlation between the X-ray flux and VHE γ-ray flux on nightly timescales is indicated with a Pearson correlation coefficient of r = 0.60 0.11. Contemporaneous spectral energy distributions (SEDs) of 1ES2344+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 1ES2344+514 from non-contemporaneous observations.

Original languageEnglish (US)
Article number169
JournalAstrophysical Journal
Volume738
Issue number2
DOIs
StatePublished - Sep 10 2011

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All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

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., ... Zitzer, B. (2011). Multiwavelength observations of the very high energy blazar 1ES 2344+514. Astrophysical Journal, 738(2), [169]. https://doi.org/10.1088/0004-637X/738/2/169