HESS J0632+057 : A new gamma-ray binary?

J. A. Hinton , J. L. Skilton , S. Funk , J. Brucker , F. A. Aharonian , G. Dubus , Armand Fiasson (1) , Yves Gallant (1) , W. Hofmann , Alexandre Marcowith (1) , O. Reimer

1 LPTA - Laboratoire de Physique Théorique et Astroparticules

The High Energy Stereoscopic System (HESS) survey of the Galactic plane hasestablished the existence of a substantial number (~40) of Galactic TeVgamma-ray sources, a large fraction of which remain unidentified. HESSJ0632+057 is one of a small fraction of these objects which is point-like innature(<2' rms), and is one of only two point-like sources that remainunidentified. Follow-up observations of this object with XMM-Newton haverevealed an X-ray source coincident with the TeV source and with the massivestar MWC 148, of the spectral type B0pe. This source exhibits a hard spectrum,consistent with an absorbed power law with Gamma = 1.26 +/- 0.04, and showssignificant variability on hour timescales. We discuss this spatial coincidenceand the implied spectral energy distribution of this object and argue that itis likely a new gamma-ray binary system with a close resemblance to the threeknown members of this class, and in particular to LS I +61 303. Further X-ray,radio and optical observations of this system are needed to firmly establishHESS J0632+057 as a new member of this rare class of Galactic objects.

Mots clés: X-rays: binaries

Domaines: Phénomènes cosmiques de haute energie [astro-ph.HE]; Phénomènes cosmiques de haute energie [astro-ph.HE]

J. A. Hinton, J. L. Skilton, S. Funk, J. Brucker, F. A. Aharonian, et al.. HESS J0632+057 : A new gamma-ray binary?. The Astrophysical journal letters, 2008, 690, pp.L101-L104. ⟨10.1088/0004-637X/690/2/L101⟩. ⟨hal-00430148⟩