Resolved very high energy gamma-ray emission of HESS J1857+026 obtained with the MAGIC telescopes

HESS J1857+026 is an extended TeV gamma-ray source that was discovered by H.E.S.S. close to the Galactic plane. Given its spatial coincidence with the young energetic pulsar PSR J1856+0245, the source might represent a pulsar wind nebula (PWN). Using data from Fermi/LAT, 7 photons above 100 GeV were associated with the source as VHE J1857+0252 by Neronov and Semikoz (2010), while no association was previously reported in MeV-GeV catalogs. HESS J1857+026 was observed with MAGIC in 2010, yielding about 30 hours of good quality stereoscopic data that resulted in a highly significant detection of the source. We present an energy spectrum together with a detailed analysis of the source morphology. We discuss the possible PWN nature of the source based on the spectral and morphological information obtained with MAGIC together with archival multi-wavelength data.