Evidence for long-term gamma-ray and X-ray variability from the unidentified TeV source HESS J0632+057

  • V. A. Acciari
  • , E. Aliu
  • , T. Arlen
  • , M. Beilicke
  • , W. Benbow
  • , D. Boltuch
  • , S. M. Bradbury
  • , J. H. Buckley
  • , V. Bugaev
  • , K. Byrum
  • , A. Cannon
  • , A. Cesarini
  • , A. Cesarini
  • , Y. C. Chow
  • , L. Ciupik
  • , P. Cogan
  • , R. Dickherber
  • , C. Duke
  • , T. Ergin
  • , A. Falcone
  • S. J. Fegan, J. P. Finley, G. Finnegan, P. Fortin, L. Fortson, A. Furniss, K. Gibbs, G. 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, S. LeBohec, G. Maier, A. McCann, M. McCutcheon, J. Millis, J. Millis, P. Moriarty, R. Mukherjee, R. A. Ong, A. N. Otte, D. Pandel, J. S. Perkins, D. Petry, M. Pohl, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, H. J. Rose, M. Schroedter, G. H. Sembroski, A. W. Smith, D. Steele, S. Swordy, M. Theiling, J. A. Toner, A. Varlotta, V. V. Vassiliev, S. Vincent, R. G. Wagner, S. P. Wakely, J. E. Ward, T. C. Weekes, A. Weinstein, T. Weisgarber, D. A. Williams, S. Wissel, M. Wood

Research output: Contribution to journalArticlepeer-review

61 Scopus citations

Abstract

HESS J0632+057 is one of only two unidentified very-high-energy gamma-ray sources which appear to be point-like within experimental resolution. It is possibly associated with the massive Be star MWC 148 and has been suggested to resemble known TeV binary systems like LS I +61 303 or LS 5039. HESS J0632+057 was observed by VERITAS for 31 hr in 2006, 2008, and 2009. During these observations, no significant signal in gamma rays with energies above 1 TeV was detected from the direction of HESS J0632+057. A flux upper limit corresponding to 1.1% of the flux of the Crab Nebula has been derived from the VERITAS data. The nondetection by VERITAS excludes with a probability of 99.993% that HESS J0632+057 is a steady gamma-ray emitter. Contemporaneous X-ray observations with the Swift X-Ray Telescope reveal a factor of 1.8 ± 0.4 higher flux in the 1-10 keV range than earlier X-ray observations of HESS J0632+057. The variability in the gamma-ray and X-ray fluxes supports interpretation of the object as a gamma-ray emitting binary.

Original languageEnglish
Pages (from-to)L94-L97
JournalAstrophysical Journal
Volume698
Issue number2
DOIs
StatePublished - Jun 20 2009

Keywords

  • Acceleration of particles
  • Binaries: general
  • Gamma rays: observations

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