AstroSat Achieves Breakthrough in Measuring X-ray Polarisation

• 06 Feb 2024

AstroSat, India's space telescope, recently successfully measured X-ray polarisation from the Cygnus X-1 black hole, a pioneering achievement in black hole studies.

Key Points

• Unveiling Black Hole Environment: Normal X-ray measurements only capture energy or intensity, while polarisation characteristics reveal details about the black hole's geometry and properties.
• Instrument Used: Measurements were made using the Cadmium Zinc Telluride Imager (CZTI), one of the five scientific instruments on board AstroSat.
• Advancing Understanding: The data inches scientists closer to understanding the mechanism of radiation production in black hole sources.
• First-Time Connection: The study connects hard X-ray radiation to the black hole jet in Cygnus X-1, addressing an open question in astrophysics.
• Photon Properties: Polarization is one of the properties carried by a photon, providing information about the close vicinity of the black hole.
• Difficult Task: Measurement of polarisation in X-ray wavelengths is a challenging task but yields valuable insights.
• ISRO's Contribution: AstroSat, launched by the Indian Space Research Organisation (ISRO) in September 2015, facilitates this groundbreaking study.
• Historical Discovery: Cygnus X-1, discovered over four decades ago, is one of the first confirmed black hole systems in our galaxy.
• Binary System: The black hole, twenty times heavier than the Sun, is in a binary system with a supergiant star, leading to the formation of a thin accretion disk responsible for soft X-rays.