Suzaku Observations of HESS J1616-508: Evidence for a Dark Particle Accelerator

We observed the bright unidentified TeV γ-ray source HESS J1616−508 with the X-ray Imaging Spectrometers onboard the Suzaku satellite. No X-ray counterpart was found to a limiting flux of 3.1 × 10 −13 ergs −1 cm −2 in the 2–10keV band, which is some 60-times below the γ-ray flux in the 1–10TeV band. This object is bright in TeV γ-rays, but very dim in the X-ray band, and thus is one of the best examples in the Galaxy of a “dark particle accelerator.” We also detected soft thermal emission with kT ∼ 0.3–0.6keV near the location of HESS J1616−508. This may be due to a dust-grain scattering halo from the nearby bright supernova remnant RCW 103.