INTEGRAL/IBIS and optical observations of the Crab nebula/pulsar polarisation

CEA, IRFU, Service d’Astrophysique, 91191 Gif-sur-Yvette, FranceAPC, 10 rue Alice Domont et Leonie Duquet, 75205 Paris Cedex 13, FranceE-mail: philippe.laurent@cea.frPrevious INTEGRAL/IBIS observations have shown that the gamma-ray radiation of the CrabNebula is highly polarised and remarkably aligned along the axis of rotation of the pulsar [4].Their study was based on the first four years of operation of the satellite. Here we present an anal-ysis based upon nearly ten years of operation. This new analysis allows a better characterisation ofthe polarisation fraction and position angle, as well as a measure of spectral energy distribution ofthe polarised component. These results are then compared to the known optical polarisation of thepulsar and nearby synchrotron knot. In the future we shall compare the gamma-ray polarisationwith the phase-resolved optical polarisation using instruments such as GASP [10].An INTEGRAL view of the high-energy sky (the first 10 years) - 9th INTEGRAL Workshop and celebrationof the 10th anniversary of the launch,October 15-19, 2012Bibliotheque Nationale de France, Paris, France