Jun 06, 2024
ASTROSAT DISCOVERS UNUSUAL BEHAVIOR AROUND BLACK HOLE
Introduction
AstroSat, India’s first dedicated multi-wavelength space observatory, has made a significant discovery regarding the black hole binary source Swift J1727.8-1613. A collaborative team of astrophysicists from U R Rao Satellite Centre (URSC), IIT Guwahati, University of Mumbai, and Tata Institute of Fundamental Research (TIFR) reported this finding in the Monthly Notices of the Royal Astronomical Society (MNRAS).
Understanding Black Holes
A black hole is a region in space with an intense gravitational pull so strong that nothing, not even light, can escape from it. This gravitational field is created when a massive star collapses under its own gravity at the end of its life cycle.
Observations by AstroSat
In the black hole X-ray binary system (BH-XRB), a black hole and its companion star are gravitationally bound. The black hole pulls matter from its companion, forming a bright accretion disk. As this matter heats up, it emits high-energy X-rays, which help scientists detect and study these black holes.
Swift J1727.8-1613, discovered on August 24, 2023, by the Swift/BAT, quickly became one of the brightest sources, with an X-ray peak value of about 7 Crab units. AstroSat first observed it on September 2, 2023, and continued monitoring it until September 14, 2023.
Key Findings
AstroSat’s study discovered unusual behavior in high-energy X-rays from Swift J1727.8-1613 during a rare outburst. This behavior, termed ‘aperiodic modulation,’ caused X-rays to exhibit a repeating pattern known as Quasi-periodic Oscillations (QPO). This is the first observation of such a pattern in this system. Over a week, the frequency of these QPOs changed from 1.4 times per second to 2.6 times per second, a unique observation in black hole studies.
Mechanism Behind QPOs
The high-energy X-rays observed were produced when lower-energy light from the disk around the black hole interacted with very hot electrons. The changing pattern of these X-rays led to the observed QPOs. QPOs are essential for understanding black holes as they provide insights into the strong gravitational forces and behavior of matter around black holes.
Tools Used
The team utilized AstroSat’s Large Area X-ray Proportional Counter (LAXPC), which has excellent time resolution and a large area for collecting photons, to study these QPOs at higher energies. Additionally, data from the NICER instrument on the International Space Station (ISS) was used to obtain a complete picture of the source’s energy output.
Conclusion
The discovery by AstroSat provides crucial insights into the behavior of black holes, contributing to our understanding of these mysterious cosmic objects. This observation marks a significant milestone in space research and highlights India’s growing capabilities in astrophysical studies.
SRIRAM’s
