Binary Merger of Gamma Ray Burst with Kilonova | 08 Dec 2022

Why in News?

Recently, a rare astronomical event involving a compact binary merger emitting long Gamma Ray Burst (GRB) twinned with a kilonova emissions was reported. This never before scientifically accepted or proven combination was also confirmed by India’s largest optical telescope, Devasthal Optical Telescope (DOT).

• The GRB lasted for over 50 seconds and identified as GRB211211A.
• Kilonovae occur when two compact objects, like binary neutron stars or a neutron star and a black hole, collide.

What are Gamma-Ray Bursts?

• About:
  • GRBs are massive but extremely bright, high-energy short gamma radiations which get released when massive stars collapse or die in the Universe.
  • They are the most powerful events in the universe, detectable across billions of light-years.
    • A light-year is the distance a beam of light travels in a single Earth year, or 9.5 trillion kilometers.
  • Astronomers classify them as long or short based on whether the event lasts for more or less than two seconds.

• Long GRBs:
  • They observe long bursts in association with the demise of massive stars.
  • When a star much more massive than the Sun runs out of fuel, its core suddenly collapses and forms a black hole.
    • Black hole refers to a point in space where matter is so compressed as to create a gravity field from which even light cannot escape.
  • As matter swirls toward the black hole, some of that escapes in the form of two powerful jets that rush outward at almost the speed of light in opposite directions.
  • Astronomers only detect a GRB when one of these jets happens to point almost directly toward Earth.
  • Each jet drills through the star, producing a pulse of gamma rays – the highest-energy form of light – that can last up to minutes. Following the burst, the disrupted star then rapidly expands as a supernova.
    • A supernova is the name given to an exploding star that has reached the end of its life.
• Short GRB:
  • Short GRB, on the other hand, forms when pairs of compact objects – such as neutron stars, which also form during stellar collapse – spiral inward over billions of years and collide.
    • A neutron star comprises one of the possible evolutionary end-points of high mass stars.

Source: IE