The active galaxy in the universe is a type of galaxy with a giant black hole at its centre. It eats a lot of gas and particles. These particles and gases revolve around the black hole in the form of disks or plates. It is scientifically called an ‘accretion disc’. Primarily, a very strong magnetic field arises mainly due to the rotation of the plasma in the accretion disc. Our sun’s magnetic field is created in exactly the same way. A very recent discovery of this cosmic magnetic field has been made with the hand of a Bengali. A few days ago, NASA announced this discovery.
Twenty scientists from eight countries, led by research scientist Shibashis Laha at NASA’s Goddard Space Flight Centre, have received indications of a polar change in the magnetic field in an active galaxy. Shibashis is an alumnus of the Physics Department of Kolkata’s Presidency College. His team’s research paper was published in The Astrophysical Journal. “This is the first time we’ve seen an indication of a polar change in the magnetic field of an active galaxy millions of times the circumference and mass of the Sun,” Shibashis said. This discovery will give us a new direction in the study of the black hole.”
An active galaxy that is 23.6 million light-years away was radiating normally at 1ES 1927 + 654. But in December 2017 the radiation suddenly started to increase there and in the next three months it became 100 times brighter at optical wavelength. After a while, X-ray radiation from the galaxy began to slowly decrease, and in the next four months it completely disappeared. But within a few months the X-ray radiation began to return slowly and by early 2021 it was back to normal. This phenomenon reverses all conventional ideas of scientists.
Near the black hole, an extremely hot (1000,000,000° Celsius) ring or plasma is formed. This hot particle ring is called Corona. The origin of the corona is due to the strong magnetic field. According to the conventional theory of the active galaxy, the accretion disk and the corona coexist. This is the first time that scientists have seen the corona disappear completely. Does this mean that the magnetic field of the active galaxy was temporarily lost?
Potential cause of the occurrence
Shibashis and his fellow scientists put forward a theory. They claim that the magnetic field at the center of the active galaxy is very strong and active. Behind the temporary loss of X-ray or magnetic field is the polar change of the magnetic field of that active galaxy. Just as our Sun changes poles every 11 years and the earth approximately in 1 million years, so too does the active galaxy. At that time, its magnetic field is lost or weakened.
On the other hand, the image of one super massive black hole was unveiled by a team of International astronomers almost 2 weeks ago. It is located at the very centre of the Milky way galaxy. The cosmic body is called Sagittarius A*.