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Bengaluru astrophysicists spot brightest object

Last Updated 05 July 2015, 20:42 IST

Two Bengaluru-based astrophysicists have identified an enigmatic cosmological object, which becomes the brightest body in the whole of the universe for a few fleeting seconds.

Located at the core of a galaxy 10 billion light years away, it is called the blazar.
It is powered by a black hole that is 250 million times as massive as the sun, and is putting out 500 billion times as much energy as the sun.

“It was a chance discovery. We were first alerted by a Russian group, which noticed the sudden increase in the brightness,” C S Stalin, an astrophysicist at Indian Institute of Science, Bengaluru and one of the members of the team that identified the blazar told Deccan Herald.

The Russians dispatched what is called astronomer’s telegram within the community asking everybody to be on the watch for this unusual source of brightness in the
sky.

Another IIA scientist Vaidehi S Paliya received the telegram in the night and the duo approached four big international telescopes including Nasa’s Swift and NuSTAR, seeking data. Moreover, observations from Himalayan Chandra Telescope located at Hanle in Ladakh were used to understand how the brightness changed.

“We have data on this blazar in all view bands that would help understand the physical processes underlying the blazar’s sudden brightness,” said Stalin.

Tracing emissions

 The understanding is important to know what happens at the centre of a galaxy, which remains outside the coverage of every telescope on the earth and space. “The core of a galaxy can be studied only by indirect methods like emissions coming from a source,” he said.  The core of a galaxy is called the “active galactic nucleus”, which is much more luminous than the rest of the galaxy.

Their extra luminosity is believed to be due to huge chunks of mass falling into a rotating supermassive black hole at the galactic core. In some cases, a small portion of the falling mass is thrown out into fine beams along the axis of rotation of the black hole, forming “jets”.

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(Published 05 July 2015, 20:42 IST)

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