Poster details
» X-ray polarization signatures in black hole accretion disks
Presenter: Vladimir Karas
Thermal emission from the accretion disc around the black hole can be polarized on its way through the atmosphere above the accretion disc. We model this effect by assuming Kerr metric for the black hole, a standard thin disc for the accretion flow and Thomson scattering in the atmosphere. We compute the expected polarization degree and the angle as they can be measured for different inclinations of the observer, optical thickness of the atmosphere and different values of the black hole spin. All relativistic effects near a compact centre are taken into account. We also assess the perspectives for the next generation of X-ray polarimeters. The expected sensitivity of the detectors onboard the planned POLARIX and IXO missions is considered. The flux level of the microquasar GRS~1915+105 in the thermal state is used in the computations. We find that the energy dependence of the polarization degree and angle will discriminate between cases with different spin of the black hole. This poster summarizes our recent results reported in a paper published in Monthly Notices of the Royal Astronomical Society (http://arxiv.org/abs/0809.0418).
Authors:- Vladimir Karas
- Michal Dovciak
- Rene W. Goosmann
- Fabio Muleri
- Giorgio Matt