Gamma Ray Bursts

Description

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Context

Photometric observations taken with the 3.6 m Devasthal Optical Telescope have provided vital information on the earliest phase of a kilonova ever detected, radically changing the understanding of scientists about the origin of Gamma Ray Bursts.

GRBs

GRBs are powerful astronomical cosmic bursts of high-energy gamma-ray.
GRBs are massive but extremely bright, high-energy short gamma radiations which get released when massive stars collapse or die in the Universe.
GRB emits more energy in a few seconds than our Sun will emit in its lifetime and has two distinct emission phases: the short-lived prompt emission (the initial burst phase that emits gamma-rays), followed by a long-lived multi-wavelength afterglow phase.

Bursts can last from ten milliseconds to several hours.
After an initial flash of gamma rays, a longer-lived "afterglow" is usually emitted at longer wavelengths (X-ray, ultraviolet, optical, infrared, microwave and radio)
The intense radiation of most observed GRBs is released during processes like creation or merging of neutron stars or black holes.
All observed GRBs have originated from outside the Milky Way galaxy.
GRBs were first detected in 1967 by the Vela satellites.

Kilonova

In recent years, scientists have discovered a special phenomenon called a kilonova of visible and infrared light with short-period GRBs, also known as a potential source of gravitational waves.
The heat produced by the radioactive decay of heavier elements may emit kilonova. This process also produces heavier elements, such as gold and platinum. However, observing kilonovas at near-infrared wavelengths is technically challenging, and only a few telescopes on Earth, including the 3.6-meter Devasthal Optical Telescope of the Aryabhatta Research Institute of Observational Sciences (ARIES), can detect kilonova and gravitational wave objects at these wavelengths upto faint limits.

New Findings

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. And traditionally, kilonova — the radiations emerging from the merger of neutron stars or any binary system — has been associated with short GRBs.
On the other hand, 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. And scientists have, so far, associated short GRBs with supernovae.
The latest study has quashed the existing understanding for at least 30 years now, as scientists were unaware of any connection between a long duration GRB and kilnovae.
The new study results clearly indicate that our classification of long and short GRBs now stands challenged.