India’s AstroSat has Made a New Discovery on the Black Hole Binary System

May 22, 2024

A group of Indian astronomers using India’s AstroSat satellite found an interesting event happening around the black hole X-ray binary system called “Swift J1727.8-1613” in August 2023. NASA’s Swift telescope was the first to see this system. AstroSat, India’s first dedicated multi-wavelength space observatory, made observations from September 2 to September 14, 2023, that led to a finding in the field of astrophysics that had never been seen before. Scientists from ISRO’s UR Rao Satellite Centre, IIT Guwahati, the University of Mumbai, and the Tata Institute of Fundamental Research all worked together to make these discoveries.

Discovery of Aperiodic Modulation of High-Energy X-rays

A group of astronomers saw a very unusual “aperiodic (irregular) modulation” of the black hole’s high-energy X-rays. In particular, in just seven days, the frequency of quasi-periodic oscillations (QPOs) in the system’s high-energy X-ray rays rose from 1.4Hz to 2.6Hz, which is a big change. In any black hole X-ray binary before, this kind of variation at certain frequencies had never been seen.

Insights into Accretion and Jet Formation

The found QPOs are very important for learning about the very harsh conditions close to black holes that are accreting matter. Low-energy photons from the accretion disc created the high-energy X-rays that were seen. These photons were then changed by hot electrons that were very close to the black hole. We can learn a lot from this finding about how gas accretion works and how relativistic jets form around black holes.

What is Black hole X-ray binary system?

A black hole X-ray binary system consists of a black hole and a normal star orbiting each other.
High-energy X-rays are emitted as the black hole accretes matter from its companion star.
Notable cases include V404 Cygni, known for its dramatic outbursts.
Cygnus X-1 is one of the earliest confirmed black holes, established via X-ray and optical observations.
GRS 1915+105 has shown highly variable jet activity.
These systems are critical in studying black hole mass and spin.
Their dynamic interactions provide insights into accretion processes and relativistic jet formation.
The first black hole X-ray binary discovered was Cygnus X-1 in 1972.

About AstroSat

AstroSat was launched by ISRO on September 28, 2015. It is India’s first dedicated multi-wavelength space telescope. It can look at objects in space like galaxies and stars in ultraviolet, optical, and X-ray wavelengths, which are very important for understanding things that happen in space. There are five main devices on the satellite, such as the Ultraviolet Imaging Telescope (UVIT) and the Soft X-ray Telescope (SXT). AstroSat’s orbit is about 650 kilometres closer to Earth than Hubble‘s. AstroSat found ultraviolet light from a galaxy 9.3 billion light-years away, making it an important tool for studying things in space that happen far away. It has also been used in more than 100 research papers, which has increased the body of information about astronomy around the world.

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