Unraveling the Mysteries of Cygnus X-1: Insights from India’s Astro Sat

Introduction
• India’s Astro Sat, a groundbreaking multi-wavelength astronomy mission, has achieved a remarkable feat by measuring the X-ray polarisation of the Cygnus X-1 black hole system. This achievement sheds light on the enigmatic nature of Cygnus X-1, one of the first confirmed black hole systems in our galaxy.
Key Facts about Cygnus X-1
• Discovered over four decades ago, Cygnus X-1 is situated at a distance approximately 400 times greater than the Earth-Sun distance. The black hole within this system is a staggering 20 times heavier than the Sun, forming a binary system with a companion heavy supergiant star, which is 40 times more massive than the Sun. The gravitational influence of the black hole triggers the spiraling of material from the supergiant, forming a thin accretion disk responsible for emitting soft X-rays.
Significance of X-ray Polarisation
• Traditionally, X-ray measurements focused solely on the energy or intensity of radiations. However, Astro Sat’s measurement of X-ray polarisation in the Cygnus X-1 system provides a unique perspective. The polarisation characteristics of X-rays, revealing the orientation of the oscillating electric field, offer valuable insights into the geometry and other properties of the black hole.
Understanding the Measurements
• Astro Sat’s observation of high polarisation in the 100-380 keV range indicates that radiation emitted from the source, particularly at energies above 100 keV, likely originates from the black hole jet. This revelation unveils a deeper understanding of the mechanisms at play within the Cygnus X-1 system, emphasizing the role of X-ray polarisation in decoding the celestial phenomena.
Conclusion
• In conclusion, India’s Astro Sat has accomplished a significant milestone in unraveling the mysteries of the Cygnus X-1 black hole system. By measuring X-ray polarisation, it has provided crucial insights into the geometry and properties of this captivating celestial entity. This achievement marks a stride forward in our comprehension of black hole dynamics and contributes to the broader field of astrophysics.