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. The 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 55647 (2009 January-2011 March) 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 321 ± 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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2011
- DOI:
- 10.1088/2041-8205/737/1/L11
- arXiv:
- arXiv:1104.4519
- Bibcode:
- 2011ApJ...737L..11B
- Keywords:
-
- gamma rays: general;
- X-rays: binaries;
- X-rays: individual: HESS J0632+057;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 12 pages, 3 figures, accepted to ApJ Letters