Brightest light in the Universe
doi:10.1038/nindia.2019.158 Published online 29 November 2019
An international team of astrophysicists has detected two massive gamma-ray bursts, the most powerful and violent events in the universe that can outshine a supernova by hundreds of times and even emit more energy in 10 seconds than the Sun will release in its lifetime1.
The short-lived bursts release high-energy photons and provide new insights into the processes that produce such energetic events.
Gamma-ray bursts are thought to arise from the formation of neutron stars or black holes. They start with bright flashes, followed by an afterglow period that releases emissions over a range of energies, from radio waves to high-energy gamma rays.
Analysing data from multiple telescopes, the researchers, including a scientist from the Saha Institute of Nuclear Physics in Kolkata, India, detected emissions from two gamma-ray bursts: GRB 190114C2 and GRB 180720B3. GRB 190114C, identified in January 2019, was found to emit very high-energy photons one minute after the burst.
They determined the mechanism responsible for such energetic emissions. They suggest that electrons scatter photons, increasing their energy through a process known as inverse Compton scattering.
Photons with energies between 100 and 440 gigaelectronvolts were observed in the afterglow, 10 hours after the initial emission of GRB 180720B, which was originally detected in July 2018.
The findings of these researches are significant since the majority of cosmic events, such as star births and star deaths, emits invisible emissions that cannot be observed using optical telescopes.
1. Veres, P. et al. Observation of inverse Compton emission from a long γ-ray burst. Nature. 575,459-463 (2019) Doi:10.1038/s41586-019-1754-6
2. Acciari, V. A. et al. Teraelectronvolt emission from the γ-ray burst GRB 190114C. Nature. 575, 455-458 (2019) Doi:10.1038/s41586-019-1750-x
3. Abdalla, H. et al. A very-high-energy component deep in the γ-ray burst afterglow. Nature. 575, 464-467 (2019) Doi:10.1038/s41586-019-1743-9