Serendipitous discovery of the unidentified extended TeV $γ$-ray source HESS J1303-631


The serendipitous discovery of an unidentified extended TeV $γ$-ray source close to the galactic plane named HESS J1303-631 at a significance of 21 standard deviations is reported. The observations were performed between February and June 2004 with the HESS stereoscopic system of Cherenkov telescopes in Namibia. HESS J1303-631 was discovered roughly 0.6° north of the binary system PSR B1259-63/SS 2883, the target object of the initial observation campaign which was also detected at TeV energies in the same field of view. HESS J1303-631 is extended with a width of an assumed intrinsic Gaussian emission profile of $σ$ = (0.16 $±$ 0.02)° and the integral flux above 380 GeV is compatible with constant emission over the entire observational period of (17 $±$ 3)% of the Crab Nebula flux. The measured energy spectrum can be described by a power-law dN/dE ˜ E-$Γ$ with a photon index of $Γ$ = 2.44 $±$ 0.05stat $±$ 0.2syst. Up to now, no counterpart at other wavelengths is identified. Various possible TeV production scenarios are discussed.

Michael Aye
Michael Aye
Research Scientist in Planetary Science

My research interests include remote sensing of surfaces, related machine learning studies and open source software.