VERITAS Reports Activity from HESS J0632+057 in Very High Energy Gamma Rays
ATel #3791; Rene A. Ong (UCLA) for the VERITAS Collaboration
on 30 Nov 2011; 18:35 UT
Credential Certification: Rene Ong (rene@astro.ucla.edu)
Subjects: Gamma Ray, >GeV, TeV, VHE, Binary
VERITAS observations of HESS J0632+057 from 21-29 November 2011 reveal an elevated gamma-ray flux level. A preliminary analysis of the 5.3-hour total exposure detects the source with a significance of more than 6 standard deviations. The estimated gamma-ray flux above 1 TeV is (6.7+-2.0)x10^-13 cm^-2 s^-1, corresponding to about 3% of the flux from the Crab Nebula above the same threshold.
HESS J0632+057 is a variable gamma-ray source (Aharonian et al. 2006, A&A, 457, 899; Acciari, V.A. et al 2009, ApJ, 698, L94), thought to be a member of the class of gamma-ray binaries, based on a 321 day periodic flux modulation revealed during long-term X-ray observations with the Swift X-ray Telescope (XRT) (Bongiorno et al. 2011, ApJ, 737, L11). It is positionally coincident, and likely associated, with the massive Be star MWC 148 (HD 259440).
The observations reported here are about 321 days after the onset of the previous gamma-ray high-state observed by VERITAS (ATel #3153) and MAGIC (ATel #3161), suggesting that the source activity will continue for the next 30 days or so. The peak of the gamma-ray emission is expected to occur around December 11th (MJD 55906+-16 days), while the X-ray emission should peak on December 25th (MJD 55920+-5 days).
VERITAS observations will continue until January, and Swift X-ray observations are expected to continue throughout this time period (A. Falcone, private communication). Observations at all wavelengths are encouraged.
