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T: Fachverband Teilchenphysik

T 59: Gammaastronomie 3

T 59.7: Vortrag

Dienstag, 28. März 2017, 18:25–18:40, H 2

Results from Observations of PSR B1259-63 with H.E.S.S. — •Thomas Murach — DESY Zeuthen, Deutschland

PSR B1259-63/LS 2883 is a binary system consisting of the massive O-type star LS 2883 and the neutron star PSR B1259-63. It is one of the seven gamma-ray binaries known to date. These systems comprise a massive star orbited by a compact object. Only for PSR B1259-63/LS 2883 the type of the compact object is known. The orbit of this neutron star is very eccentric, resulting in small spatial separations of the two stars of less than 1 AU around periastron. Close to periastron, the neutron star crosses the circumstellar disk around the host star twice. Due to the variable interactions in this system, variable emission of light is observed in all wavelength bands.
PSR B1259-63/LS 2883 was observed with the H.E.S.S. telescopes in Namibia around the times of four different periastron passages. Extended observations were conducted with the full H.E.S.S.-II array around the 2014 periastron, for the first time covering the time of periastron itself as well as parts of the orbit before the first disk crossing and during the GeV flare observed by Fermi-LAT. Results from these recent observations are presented. Due to the inclusion of data taken with the large telescope in the centre of the H.E.S.S. array, the energy threshold of 200 GeV is unprecedentedly low for this source. A local flux minimum is observed at the time of periastron. High flux states are observed at the time of the GeV flare and, unexpectedly, before the first disk crossing. Predictions derived from a leptonic model are found to agree well with observations.