Multiwavelength Study of HESS J1809-193

HESS J1809-193 is an extended TeV gamma-ray source in the Galactic Plane. Multiwavelength observations of the HESS J1809-193 field reveal a complex picture. We present results from three CXO and two Suzaku observations of a region in the northeastern outskirts of HESS J1809-193, where enhanced TeV emission has been reported. Our analysis also includes GeV gamma-ray and radio data. One of the X-ray sources in the field is the X-ray binary XTE J1810-189, for which we present the outburst history from multiple observatories and confirm that XTE J1810-189 is a strongly variable type I X-ray burster, which can hardly produce TeV emission. We investigate whether there is any connection between the possible TeV extension of HESS J1809-193 and the sources seen at lower energies. We find that another X-ray binary candidate, Suzaku J1811-1900, and a radio supernova remnant, SNR G11.4-0.1, can hardly be responsible for the putative TeV emission. Our multiwavelength classification of fainter X-ray point sources also does not produce a plausible candidate. We conclude that the northeast extension of HESS J1809-193, if confirmed by deeper observations, can be considered as a dark accelerator – a TeV source without visible counterpart at lower energies. Read the full text here.

On the right is the MW coverage of the Suzaku X-ray source J1811. All the images are 15′ × 13′ and aligned. Upper Left: Suzaku 0.5 to 10 keV smoothed image, with contour levels spaced linearly in brightness. Darker color corresponds to brighter X-ray emis- sion. The contours are overlaid on the other images. The red cross marks the nominal position of the compact source. Upper Right: Hα image from the SuperCOSMOS Hα Survey (Parker et al. 2005). Darker color corresponds to brighter Hα emission. Lower Left: 1.4 GHz VLA radio image from the Multi-Array Galactic Plane Imaging Survey (White et al. 2005). Lighter colors emphasize brighter radio emission. Lower Right: Spitzer MIPS 24 μm image of the source region. Lighter colors emphasize brighter IR emission.

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