Veritas observations of the γ-ray binary LS i +61 303

V. A. Acciari, M. Beilicke, G. Blaylock, S. M. Bradbury, J. H. Buckley, V. Bugaev, Y. Butt, K. L. Byrum, O. Celik, A. Cesarini, L. Ciupik, Y. C.K. Chow, P. Cogan, P. Colin, W. Cui, M. K. Daniel, C. Duke, T. Ergin, A. D. Falcone, S. J. FeganJ. P. Finley, P. Fortin, L. F. Fortson, D. Gall, K. Gibbs, G. H. Gillanders, J. Grube, R. Guenette, D. Hanna, E. Hays, J. Holder, D. Horan, S. B. Hughes, C. M. Hui, T. B. Humensky, P. Kaaret, D. B. Kieda, J. Kildea, A. Konopelko, H. Krawczynski, F. Krennrich, M. J. Lang, S. Lebohec, K. Lee, G. Maier, A. Mccann, M. Mccutcheon, J. Millis, P. Moriarty, R. Mukherjee, T. Nagai, R. A. Ong, D. Pandel, J. S. Perkins, F. Pizlo, 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, J. A. Toner, L. Valcarcel, V. V. Vassiliev, R. Wagner, S. P. Wakely, J. E. Ward, T. C. Weekes, A. Weinstein, R. J. White, D. A. Williams, S. A. Wissel, M. Wood, B. Zitzer

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Abstract

LS I+61 303 is one of only a few high-mass X-ray binaries currently detected at high significance in very high energy γ-rays. The system was observed over several orbital cycles (between 2006 September and 2007 February) with the VERITAS array of imaging air Cerenkov telescopes. A signal of γ-rays with energies above 300 GeV is found with a statistical significance of 8.4 standard deviations. The detected flux is measured to be strongly variable; the maximum flux is found during most orbital cycles at apastron. The energy spectrum for the period of maximum emission can be characterized by a power law with a photon index of Γ = 2.40 ± 0.16stat ± 0.2sys and a flux above 300 GeV corresponding to 15%-20% of the flux from the Crab Nebula.

Original languageEnglish (US)
Pages (from-to)1427-1432
Number of pages6
JournalAstrophysical Journal
Volume679
Issue number2
DOIs
StatePublished - Jun 1 2008

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All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Acciari, V. A., Beilicke, M., Blaylock, G., Bradbury, S. M., Buckley, J. H., Bugaev, V., Butt, Y., Byrum, K. L., Celik, O., Cesarini, A., Ciupik, L., Chow, Y. C. K., Cogan, P., Colin, P., Cui, W., Daniel, M. K., Duke, C., Ergin, T., Falcone, A. D., ... Zitzer, B. (2008). Veritas observations of the γ-ray binary LS i +61 303. Astrophysical Journal, 679(2), 1427-1432. https://doi.org/10.1086/587736