Astronomers Capture Supernova From Distant Galaxy

When a massive star dies, it explodes in a spectacular celestial fireworks show. For a brief time, it outshines the galaxy enough to be seen by telescopes from Earth. This event happened in May in a galaxy nearly 21 million light years away from Earth. The explosion, dubbed SN 2023ixf, was captured by amateur astronomers worldwide, including some from India. It was the first time a radio signal at a specific wavelength, known as the hydrogen line, had been detected from a galaxy so far away.

Neutral hydrogen atoms emit the 21-centimeter line. It can be detected by a particular type of radio telescope that captures the radiation emitted by galaxies. Astronomers hope to use this new technique to study our universe’s earliest stars and galaxies.

But how do these titanic explosions occur? First, its core collapses when a supergiant star runs out of nuclear fuel at the center. This creates immense pressure that pushes outward on the star’s outer layers and causes them to explode.

The star sheds its outer layer into space during this process, leaving behind a hot, dense core. Depending on size, This core can produce either a neutron star or a black hole. Understanding this process has consumed astronomers for decades.

Astronomers have finally achieved a milestone in their quest to understand the origins of these cosmic fireworks. They have discovered a radio signal transmitted by the exploding star and picked up by the Giant Metrewave Radio Telescope in India. This signal is the most distant ever recorded and allows scientists to probe the early galaxies of our universe.

“It’s the equivalent of a look-back in time at the very early stage of the universe,” said Arnab Chakraborty, an assistant professor at McGill University in Canada and co-author of the study that reveals this finding. Galaxies emit radiation across various radio wavelengths, but it was previously impossible to capture them from galaxies so far away.

The signal, identified by its wavelength as H-lines or hydrogen lines, was detected at a frequency of 10.5 gigahertz. It was emitted by a dying Wolf-Rayet (WR) star that collapsed into a neutron star, leaving behind a supernova. The astronomers tracked the radio wave’s path to its destination in the early galaxy, which they dubbed SDSSJ0826+5630. They also found evidence that the galaxies in between acted as a lens, magnifying the incoming signal and making it easier for the telescope to detect. The team continues to observe the supernova and its remnants to place tighter constraints on its explosion mechanism and its progenitor system. They have published their results in the journal ‘Monthly Notices of the Royal Astronomical Society.’ The paper was co-authored by astronomers Kuntal Misra, Anjasha Gangopadhyay, and Raya Dastidar from the Indian Institute of Astrophysics (ARIES), Fahd Bin Abdul Hasis from the Indian Space Research Organisation and Kiran Mohan from the Liquid Propulsion Systems Centre (LPSC).