Prof. Henric Krawczynski from Washington University in Saint Louis and McDonnell Center for the Space Sciences will hold the „X-Ray Spectropolarimetric Observations of Black Holes and Neutron Stars with X-Calibur” seminar on 18 June at 11 a.m. in the Studio Room, Tower Building.Abstract:

„X-ray polarimetry promises to give qualitatively new information about high-energy astrophysical sources such as black holes in X-ray binaries, mass accreting supermassive black holes, mass accreting neutron stars, X-ray bright pulsars, magnetars, and gamma-ray bursts. We have developed a scattering polarimeter (X-Calibur) which can be used in the focal plane of a grazing incidence X-ray mirror assembly. X-Calibur combines a low-Z scatterer with an assembly of pixelated Cadmium Zinc Telluride (CZT) detectors to achieve excellent detection efficiency over the broad 20-70 keV energy range. In this talk I will discuss the design and test of the polarimeter and the scientific objectives of two upcoming X-Calibur balloon flights (Fall 2016 from Fort Sumner, NM, and 2018/2019 from McMurdo, Ross Island). Furthermore, I will present the results of general relativistic ray tracing studies which we carried through to elucidate the potential of X-ray polarimetric observations with X-Calibur and with a space-borne version of X-Calibur (called PolSTAR) to test the theory of general relativity in the strong gravity regime.”