Evidence for long-term Gamma-ray and X-ray variability from the unidentified TeV source HESS J0632+057
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 hours 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 non-detection by VERITAS excludes with a probability of 99.993% that HESS J0632+057 is a steady gamma-ray emitter. Contemporaneous X-ray observations with Swift XRT 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 ob ject as a gamma-ray emitting binary.
Keywords
Cite
@article{arxiv.0905.3139,
title = {Evidence for long-term Gamma-ray and X-ray variability from the unidentified TeV source HESS J0632+057},
author = {VERITAS Collaboration and V. A. Acciari and E. Aliu and T. Arlen and M. Beilicke and W. Benbow and D. Boltuch and S. M. Bradbury and J. H. Buckley and V. Bugaev and K. Byrum and A. Cannon and A. Cesarini and A. Cesarini and Y. C. Chow and L. Ciupik and P. Cogan and R. Dickherber and C. Duke and T. Ergin and A. Falcone and S. J. Fegan and J. P. Finley and G. Finnegan and P. Fortin and L. Fortson and A. Furniss and K. Gibbs and G. H. Gillanders and J. Grube and R. Guenette and G. Gyuk and D. Hanna and J. Holder and D. Horan and C. M. Hui and T. B. Humensky and A. Imran and P. Kaaret and N. Karlsson and M. Kertzman and D. Kieda and J. Kildea and A. Konopelko and H. Krawczynski and F. Krennrich and M. J. Lang and S. LeBohec and G. Maier and A. McCann and M. McCutcheon and J. Millis and P. Moriarty and R. Mukherjee and R. A. Ong and A. N. Otte and D. Pandel and J. S. Perkins and D. Petry and M. Pohl and J. Quinn and K. Ragan and L. C. Reyes and P. T. Reynolds and H. J. Rose and M. Schroedter and G. H. Sembroski and A. W. Smith and D. Steele and M. Theiling and J. A. Toner and A. Varlotta and V. V. Vassiliev and S. Vincent and R. G. Wagner and S. P. Wakely and J. E. Ward and T. C. Weekes and A. Weinstein and T. Weisgarber and D. A. Williams and S. Wissel and M. Wood},
journal= {arXiv preprint arXiv:0905.3139},
year = {2011}
}
Comments
8 pages, 3 figures, Accepted for publication in The Astrophysical Journal