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R. C. G. Chaves

Publications and source records attributed to R. C. G. Chaves.

111 records · Page 7Linked to original sources

Extending the H.E.S.S. Galactic Plane Survey

The High Energy Stereoscopic System (H.E.S.S.), located in the Khomas Highlands of Namibia, is an array of four imaging atmospheric-Cherenkov telescopes designed to detect gamma-rays in the very-high-energy (VHE; E > 100 GeV) domain. It is an ideal instrument for surveying the Galactic plane in search of new sources of VHE gamma-rays, due to its location in the Southern Hemisphere, its excellent sensitivity, and its large field-of-view. The H.E.S.S. Galactic Plane Survey (GPS) began in 2004 and initial observations of the Galactic plane resulted in the discovery of numerous VHE gamma-ray emitters. This original H.E.S.S. GPS covered the inner Galaxy within +/- 30 deg in longitude and +/- 3 deg in latitude. In the last four years, the longitudinal extent of the survey has more than doubled, now including the region l = 275 deg - 60 deg, and the exposure in the inner Galaxy has also been significantly increased. These efforts have consequently led to the discovery of many previously-unknown VHE gamma-ray sources with high statistical significance. We report on the current status of this ongoing, extended H.E.S.S. GPS, present the latest images of the survey region, and highlight the most recent discoveries.

astro-ph.HE↗

New unidentified H.E.S.S. Galactic sources

H.E.S.S. is one of the most sensitive instruments in the very high energy (VHE; > 100 GeV) gamma-ray domain and has revealed many new sources along the Galactic Plane. After the successful first VHE Galactic Plane Survey of 2004, H.E.S.S. has continued and extended that survey in 2005-2008, discovering a number of new sources, many of which are unidentified. Some of the unidentified H.E.S.S. sources have several positional counterparts and hence several different possible scenarios for the origin of the VHE gamma-ray emission; their identification remains unclear. Others have so far no counterparts at any other wavelength. Particularly, the lack of an X-ray counterpart puts serious constraints on emission models. Several newly discovered and still unidentified VHE sources are reported here.

astro-ph.HE↗

On the nature of HESS J1503-582 revealed by the H.E.S.S. experiment: Coincidence with a FVW?

The H.E.S.S. survey of the inner Galaxy in the very-high-energy gamma-ray domain has led to the discovery of many extended sources, some of which do not appear to be associated with any obvious counterpart at traditional wavelengths (radio, infrared and X-ray). In this contribution, preliminary H.E.S.S. results on one of these so-called "dark" sources, namely HESS J1503-582, are presented. After introducing the properties of this source candidate, results of the search for counterparts in several astronomical windows are shown. Finally, its possible association with a "Forbidden-Velocity-Wing", a characteristic 21 cm HI line structure that appears as a deviation from the canonical Galactic rotation curve, is discussed.

astro-ph↗