Mózsi Kiss: Hard X-ray polarimetry of Cygnus X-1 with XL-Calibur

Thursday 18 Sept 2025, 13:15 → 14:00 Europe/Stockholm

AlbaNova Main Building

XL-Calibur is a balloon-borne Compton telescope measuring hard X-ray polarization in the ~15-80 keV energy range. In the summer of 2024, the instrument conducted a week-long stratospheric flight from Sweden to Canada. The X-ray binary system Cygnus X-1 was successfully observed, providing the most precise constraint to date of the hard X-ray polarization from such a system. Along with soft X-ray polarimetric data from the IXPE satellite in the 2-8 keV range, results can help constrain the origin of the X-ray emission.

 

In this talk, we will discuss the XL-Calibur telescope (part of which was built and tested in the astrophysics lab at AlbaNova), its performance during the 2024 flight, and results from the Cygnus X-1 observations. An outlook to the future of XL-Calibur will also be provided, together with a hint of a Cygnus analysis currently in the pipeline.