Accretion geometry of the black-hole binary Cygnus X-1 from X-ray polarimetry

Understand

Black-hole binary (BHB) systems comprise a stellar-mass black hole and a closely orbiting companion star.

• Matter is transferred from the companion to the black hole, forming an accretion disk, corona and jet structures.
• The resulting release of gravitational energy leads to emission of X-rays.
• The radiation is affected by special/general relativistic effects, and can serve as a probe of the properties of the black hole and surrounding environment, if the accretion geometry is properly identified.