A New Tev Binary: The Discovery Of An Orbital Period In Hess J0632+057
Abstract
HESS J0632+057 is a variable, point-like source of Very High Energy (> 100 GeV) gamma-rays located in the Galactic plane. It is positionally coincident with a Be star, it is a variable radio and X-ray source, has a hard X-ray spectrum, and has low radio flux. These properties suggest that the object may be a member of the rare class of TeV/X-ray binary systems. A definitive confirmation of this would be the detection of a periodic orbital modulation of the flux at any wavelength. We have obtained Swift X-ray telescope observations of the source from MJD 54857 to 55690 (Jan. 2009 - May 2011) to test the hypothesis that HESS J0632+057 is an X-ray/TeV binary. We show that these data exhibit flux modulation with a period of 320 ± 5 days, and we evaluate the significance of this period by calculating the null hypothesis probability, allowing for stochastic flaring. This periodicity establishes the binary nature of HESS J0632+057. We also report the spectral energy distribution, which will be used to constrain geometry and models of gamma-ray generation in the system.
- Publication:
-
AAS/High Energy Astrophysics Division #12
- Pub Date:
- September 2011
- Bibcode:
- 2011HEAD...12.1320B