Our knowledge of the most violent explosions in the Universe is being fundamentally altered by a sudden burst of light from a galaxy just over a billion light-years away.
The apparent cause of the gamma-ray burst is the merger of two neutron stars. This isn’t shocking in and of itself because neutron stars can eject a brief, strong burst of high-energy radiation when they collide.
The length of the eruption is what shocks you. The duration of the gamma radiation flare was 50 seconds, which was previously thought to be exclusive to supernova explosions.
According to astrophysicist Chris Fryer of the Los Alamos National Laboratory, “astronomers have long believed that gamma-ray bursts fell into two categories: long-duration bursts from implosion stars and short-duration bursts from merging compact stellar objects.”
This straightforward picture has been complicated by the discovery of a kilonova and a long-duration gamma-ray burst in a recently witnessed event.
The radioactive disintegration of atomic nuclei produces the most energetic type of light in the universe, known as gamma radiation. The energy released by a gamma-ray burst, which is enormous, is equivalent to what the Sun would emit in 10 billion years. These strong light flashes can only be created by extraordinarily violent occurrences.
We first witnessed how these catastrophes can play out in 2017 when light from a neutron star collision reached Earth. It spoke of a kilonova explosion, which was between a classical nova and a supernova in terms of power, and a brief gamma-ray burst. When considered as a whole, the entire light spectrum provided us with a guide for understanding equally brief gamma radiation bursts.
Additionally, a wide variety of long-duration gamma-ray bursts from supernovae have been seen by researchers. A large star reaches its end of life at that point, gets unstable, and explodes.
When the long-duration gamma-ray burst (later known as GRB211211A) was discovered in December of last year, scientists pointed their telescopes toward the direction of the afterglow that typically accompanies such an explosion. They were shocked to discover an item that faded too quickly to be a supernova as well as an abundance of infrared radiation.
“There are a lot of objects in our night sky that fades quickly,” says astrophysicist Wen-fai Fong of Northwestern University.
“We picture a source through various filters to gather color data that aids in identifying the source. Red was the dominant color here, and bluer hues faded more swiftly. Kilonovae can only result from neutron star mergers, and this color evolution is a telltale sign of one.”
More intriguing details about the incident emerged through our investigation of it. One young galaxy still in the throes of star formation was discovered when the event was traced to its host galaxy, which is 1.1 billion light-years away. This is extremely dissimilar to the old, dormant, starless galaxy that gave rise to the 2017 collision. This suggests that a broader spectrum of galaxy types may need to be included in the search for kilonova events.
Additionally, neutron star mergers are the source of heavy metals like gold and platinum, as was demonstrated by the merger in 2017. A group of researchers used a model to analyze the GRB211211A emission and discovered that the explosion produced almost 1,000 times the mass of Earth in heavy elements.
We don’t exactly know why the event’s duration was so different at this point. The gamma-ray explosion was the only aspect that did not meet the profile of a neutron star merger, which, according to astronomers, opens up some really intriguing possibilities.
“This gamma-ray burst was extraordinary. Mergers shouldn’t last longer than two seconds, at most. This one managed to run a jet for about a minute. We can’t rule out the possibility that what we observed was a neutron star being torn apart by a black hole, but it’s feasible that the behavior may be described by a long-lasting neutron star “said Benjamin Gompertz, an astronomer at the University of Birmingham in the UK.
We will be able to choose the correct response after studying more of these events, and the in-depth knowledge we got from GRB 211211A will be crucial for this interpretation.
Five publications that were published in Nature provided analysis of the event. Here, here, here, here, and here are where you can locate them.