Why is it in the News?

Northwestern University recently confirmed that the brightest gamma-ray burst ever recorded, GRB 221009A, was caused by the collapse and explosion of a massive star.

About GRB 221009A:

• GRB 221009A, also known as Swift J1913.1+1946, is the brightest gamma-ray burst ever detected, estimated to be ten times brighter than the previous record holder.
• The burst itself lasted around seven minutes, but its effects were observable for over ten hours.
• GRB 221009A originated from a galaxy estimated to be 2.4 billion light-years away, yet it was powerful enough to influence Earth's atmosphere.
• This exceptionally bright burst emitted across a vast range of the electromagnetic spectrum, providing a unique opportunity for scientists to study this rare phenomenon in detail.
• The cause of the burst is attributed to the collapse of a massive star, but scientists are still investigating why it was so much brighter than other gamma-ray bursts.

What are Gamma-ray Bursts?

• Gamma-ray bursts (GRBs) are the most powerful explosions in the universe.
• These brief flashes of high-energy light result from some of the universe's most explosive events, including the birth of black holes and collisions between neutron stars.
• Lasting a few milliseconds to several minutes, GRBs can be hundreds of times brighter than an average supernova, making them as luminous as a million trillion suns.
• Thus, when a GRB erupts, it briefly becomes the brightest source of electromagnetic radiation in the observable universe.
• Gamma Ray Bursts are difficult to study because they are so short-lived.
• They were first detected by the Vela satellites, which were designed to detect nuclear tests during the Cold War.
• It was only years after their detection that they were declassified.
• The location of gamma-ray bursts within their host galaxy and their surrounding environment informs us as to the formation and evolution of the progenitor system, providing insight into stellar evolution and star formation across the age of the universe.

What causes a gamma-ray burst?

• The cause of a gamma-ray burst depends on how long it lasts.
• GRBs that last less than two seconds are caused by the merger of two neutron stars or the merger of a neutron star and a black hole.
• Longer GRBs, which can last hours, are triggered when a massive star collapses and births a black hole.
• In both cases, GRBs result from jets of particles accelerated to around 99.9% of the speed of light.

How powerful are gamma-ray bursts?

• In just a few seconds, a gamma-ray burst can emit as much energy as the sun will put out over its entire 9 billion-year lifetime

Do gamma-ray bursts happen in the Milky Way?

• GRBs seem to be most closely associated with galaxies that are in the midst of intense star formation, a period that our galaxy seems to have matured out of 2 billion to 3 billion years ago.
• However, the Milky Way is filled with the supernova remnants that mark the deaths of massive stars, indicating that our galaxy was once home to GRBs.