First data taken by the 3.6-meter telescope detects unexpected kilonova emission from ‘a long-duration gamma-ray burst’

Source: The post is based on the article “First data taken by the 3.6-meter telescope detects unexpected kilonova emission from ‘a long-duration gamma-ray burst” published in PIB on 8th December 2022

What is the News?

A team of astronomers has recorded a rare astronomical event involving a compact binary merger emitting long Gamma Ray Burst(GRB) twinned with a kilonova emission — a never before scientifically accepted or proven combination.

Significantly, India’s largest optical telescope — the 3.6 metres Devasthal Optical Telescope (DOT) was among the key global telescopes that together confirmed this rare combination.

What are Gamma Ray Burst(GRBs)?

GRBs are massive but extremely bright, high-energy short gamma radiations which get released when massive stars collapse or die in the Universe. 

In fact, the energy associated with GRBs is many folds larger than what our Sun can emit in its entire lifetime, making its study key to understanding the life and death of stars in our Universe.

Types of GRBs

Short GRBs: When a pair of binary compact systems — either two blackholes, dense celestial bodies or neutron stars — rotate in a spiral fashion for billions of years, their ultimate merger leads to release of short GRBs. These emissions last for less than two seconds. 

Long GRBs: When very massive stars die, the event results in the release of long GRBs and the associated gamma radiations last for more than two seconds or longer. 

What is Kilonova?

A kilonova is a transient astronomical event that occurs in a compact binary system when two neutron stars or a neutron star and a black hole merge. Traditionally, kilonova has been associated with short GRBs.

What have the scientists found?

Scientists have recorded a rare astronomical event involving a compact binary merger emitting a long Gamma Ray Burst(GRB) named GRB211211A twinned with a kilonova emission. However, the properties of long-duration GRB were missing making the event unusual.

Significance of this finding: These findings have quashed the existing understanding for at least 30 years now, as scientists were unaware of any connection between a long-duration GRB and kilnovae.

This could then mean that some processes are common between the long and short GRBs and their scientific classification now stands challenged.