Direkt zum InhaltDirekt zur SucheDirekt zur Navigation
▼ Zielgruppen ▼

Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - Experimentelle Elementarteilchenphysik

The H Collaboration (2011)

Revisiting the Westerlund 2 field with the HESS telescope array

aap, 525:A46+.

Aims: Previous observations with the HESS telescope array revealed the existence of extended very-high-energy (VHE; E>100 GeV) gamma-ray emission, HESS J1023-575, coincident with the young stellar cluster Westerlund 2. At the time of discovery, the origin of the observed emission was not unambiguously identified, and follow-up observations have been performed to further investigate the nature of this gamma-ray source. Methods: The Carina region towards the open cluster Westerlund 2 has been re-observed, increasing the total exposure to 45.9 h. The combined dataset includes 33 h of new data and now permits a search for energy-dependent morphology and detailed spectroscopy. Results: A new, hard spectrum VHE gamma-ray source, HESS J1026-582, was discovered with a statistical significance of 7sigma. It is positionally coincident with the Fermi LAT pulsar PSR J1028-5819. The positional coincidence and radio/gamma-ray characteristics of the LAT pulsar favors a scenario where the TeV emission originates from a pulsar wind nebula. The nature of HESS J1023-575 is discussed in light of the deep HESS observations and recent multi-wavelength discoveries, including the Fermi LAT pulsar PSR J1022-5746 and giant molecular clouds in the region. Despite the improved VHE dataset, a clear identification of the object responsible for the VHE emission from HESS J1023-575 is not yet possible, and contribution from the nearby high-energy pulsar and/or the open cluster remains a possibility.

Provided by the SAO/NASA Astrophysics Data System