INTEGRAL OBSERVATIONS OF GAMMA-RAY POLARIZED SOURCES

P. Laurent

In complement to spectro-imaging observations, gamma-ray polarimetry provides a unique in-sight into the geometry and magnetic configuration of compact gamma-ray sources, such as neutron stars or black holes. Due to the unprecedented spectral and timing capabilities of Integral, and thanks to its coded mask imaging technics, which efficiently suppresses most of the background contribution, we have measured linearly polarized emission from the brightest cosmic high energy sources. We were able to measure for the first time, at energies above 200 keV, a clear signal from several gamma-ray sources such as the Crab pulsar, the black hole candidate Cygnus X-1, and Gamma-Ray Bursts. These observations have enabled us to put strong constraints on the physical process at work in these sources. After a short review of Compton polarimeter principles, I will describe these Integral results and their implication on our knowledge of compact objects.