July 29, 2015 to August 6, 2015
World Forum
Europe/Amsterdam timezone

HESS J1641-463, a very hard spectrum TeV gamma-ray source in the Galactic plane

Aug 4, 2015, 4:00 PM
Mississippi Foyer (World Forum)

Mississippi Foyer

World Forum

Churchillplein 10 2517 JW Den Haag The Netherlands
Board: 77
Poster contribution GA-EX Poster 3 GA


Igor Oya (DESY Zeuthen)


HESS J1641-463 is a unique source discovered by the H.E.S.S. telescope array in the very-high energy (VHE, E >= 0.1 TeV) domain. The source had been previously hidden in the extended tail of emission from the bright nearby source HESS J1640-465. However, the analysis of the VHE data from the region at energies above 4 TeV revealed this new source at a significance level of 8.5 sigma. HESS J1641-463 showed a moderate flux level F(E > 1 TeV) = (3.64 +/- 0.44_stat +/- 0.73_sys) x 10^-13 cm^-2s^-1, corresponding to 1.8% of the Crab Nebula flux above the same energy, and a hard spectrum with a photon index Gamma = 2.07 +/- 0.11_stat +/- 0.20_sys. The light curve was investigated for evidence of variability, but none was found on both short (28-min observation) timescales and long (yearly) timescales. HESS J1641-463 is positionally coincident with the radio supernova remnant SNR G338.5+0.1. There is no clear X-ray counterpart of the SNR, although Chandra and XMM-Newton data reveal some weak emission that may be associated. If the emission from HESS J1641-463 is produced by cosmic ray protons colliding with the ambient gas, then the proton spectrum extends up to at least 0.1 PeV (99% confidence limit. If this is the case, then HESS J1641-463 may be a member of a larger source population contributing to the Galactic cosmic-ray flux around the knee.
Registration number following "ICRC2015-I/" 310
Collaboration H.E.S.S.

Primary author

Igor Oya (DESY Zeuthen)


Felix Aharonian (Max Planck fuer Kernphysik) Matthiew Dalton (Université Bordeaux 1, CNRS/IN2P3, Centre d'Études Nucléaires de Bordeaux Gradignan) Sabrina Casanova (Max Planck fuer Kernphysik)

Presentation materials