160 articles – 2214 references  [version française]
 HAL: in2p3-00738825, version 1
 Astronomy and Astrophysics 544 (2012) A3
 Fermi-LAT constraints on the Pulsar Wind Nebula nature of HESS J1857+026
 (2012)
 Since its launch, the Fermi satellite has firmly identified 5 pulsar wind nebulae plus a large number of candidates, all powered by young and energetic pulsars. HESS J1857+026 is a spatially extended gamma-ray source detected by H.E.S.S. and classified as a possible pulsar wind nebula candidate powered by PSR J1856+0245. We search for gamma-ray pulsations from PSR J1856+0245 and explore the characteristics of its associated pulsar wind nebula. Using a rotational ephemeris obtained from the Lovell telescope at Jodrell Bank Observatory at 1.5 GHz, we phase-fold 36 months of gamma-ray data acquired by the Large Area Telescope (LAT) aboard Fermi. We also perform a complete gamma-ray spectral and morphological analysis. No gamma-ray pulsations were detected from PSR J1856+0245. However, significant emission is detected at a position coincident with the TeV source HESS J1857+026. The gamma-ray spectrum is well described by a simple power-law with a spectral index of 1.53 \pm 0.11_{\rm stat} \pm 0.55_{\rm syst}$and an energy flux of$G(0.1$--100 GeV$)=(2.71 \pm 0.52_{\rm stat} \pm 1.51_{\rm syst}) \times 10^{-11}$ergs cm$^{-2}$s$^{-1}$. The$\gamma$-ray luminosity is$L_{PWN}^{\gamma} (0.1$--100 GeV$)=(2.5 \pm 0.5_{stat} \pm 1.5_{syst}) \times 10^{35} (\frac{d}{9 kpc})^2$ergs s$^{-1}$, assuming a distance of 9 kpc. This implies a$\gamma-$ray efficiency of$\sim$5% for$\dot{E}=4.6 \times 10^{36}$erg$s^{-1}\$, in the range expected for pulsar wind nebulae. Detailed multi-wavelength modeling provides new constraints on its pulsar wind nebula nature.
 Research team: GLAST
 Subject(s) : Physics/Astrophysics/High Energy Astrophysical PhenomenaSciences of the Universe/Astrophysics/High Energy Astrophysical Phenomena
 in2p3-00738825, version 1 http://hal.in2p3.fr/in2p3-00738825 oai:hal.in2p3.fr:in2p3-00738825 From: Nathalie Martin <> Submitted for: David SMITH <> Submitted on: Friday, 5 October 2012 11:30:10 Updated on: Monday, 8 October 2012 11:41:37