Overview
- An international team reports in The Astrophysical Journal the most precise constraints yet on the degree and angle of hard X-ray polarization from Cygnus X-1.
- The results come from XL-Calibur’s six-day stratospheric flight from Sweden to Canada in July 2024.
- Polarization measurements probe the geometry of the accretion environment, offering insights not available from brightness or spectra alone.
- Researchers plan to combine the balloon data with observations from NASA’s IXPE mission to test state-of-the-art simulations of black hole physics.
- The collaboration plans a follow-up Antarctic flight in 2027 to expand observations to additional black holes and neutron stars.