2012/06/14 by R. Rousseau, M. -H. Grondin, A. Van Etten +13 · 1 citation
Physics and Astronomy · #astro-ph.HE
paper · pdf · doi:10.1051/0004-6361/201118685
A&A - Year: 2012 Accepted: 05/23/12
arxiv created 2012/06/14 · arxiv updated 2012/06/18
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 ± 0.11\rm stat ± 0.55\rm syst and an energy flux of G(0.1--100 GeV)=(2.71 ± 0.52\rm stat ± 1.51\rm syst) × 10-11 ergs cm-2 s-1. The γ-ray luminosity is LPWNγ (0.1--100 GeV)=(2.5 ± 0.5stat ± 1.5syst) × 1035 ((d)/(9 kpc))2 ergs s-1, assuming a distance of 9 kpc. This implies a γ-ray efficiency of ∼ 5% for E=4.6 × 1036 erg s-1, in the range expected for pulsar wind nebulae. Detailed multi-wavelength modeling provides new constraints on its pulsar wind nebula nature.