2011/04/30 by Stephen Bongiorno, Abraham Falcone, Michael Stroh +5 · 1 citation
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.1088/2041-8205/737/1/l11
12 pages, 3 figures, accepted to ApJ Letters
arxiv created 2011/07/11 · arxiv updated 2015/05/27
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 \it Swift X-ray telescope observations of the source from MJD 54857 to 55647 (Jan. 2009 - Mar. 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 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.