(ORDO NEWS) — A powerful burst of light from a galaxy a billion light-years away is reshaping our understanding of the most powerful explosions in the universe.
The gamma-ray burst appears to be the result of the merger of two neutron stars. This in itself is not a surprise; neutron stars can emit a short, intense burst of high-energy radiation when they collide with each other.
What is a blow is the duration of the ejection. The burst of gamma radiation lasted 50 seconds. Previously, it was believed that such a duration is associated only with supernova explosions.
“Astronomers have long believed that gamma-ray bursts fall into two categories: long bursts of exploding stars. and short bursts from the merger of compact stellar objects,” explains astrophysicist Chris Fryer of Los Alamos National Laboratory.
“But in a recent observed event, we found a kilonova along with a long-ray burst, and this distorted this simple picture.”
Gamma radiation is the most energetic form of light in the universe, a product of the radioactive decay of atomic nuclei. And a gamma-ray burst is huge, releasing as much energy in a few seconds as the Sun would produce in 10 billion years. Only extremely strong events can cause such powerful flashes of light.
When the light from a neutron star collision hit Earth in 2017, we saw for the first time how these events could unfold.
It described a kilonova explosion between a classical nova and a supernova in strength accompanied by a relatively short gamma-ray burst. Taken together, the full spectrum of light has given us a blueprint for interpreting these short bursts of gamma rays.
Researchers have also observed a wide range of long-lasting bursts of gamma rays from supernovae. That’s when the massive star reaches the end of its life, becomes unstable, and explodes.
When a long-lasting gamma-ray burst (subsequently named GRB211211A) was observed last December, astronomers turned their telescopes to take a look at the afterglow that usually follows such an explosion. To their surprise, they found an object that was dimming too fast to be a supernova and an excess of infrared light.
“There are many objects in our night sky that are rapidly fading,” says astrophysicist Wen. — Fai Fong from Northwestern University.
“We display the source in different filters to get color information that helps us identify the identity of the source. In this case, the red color dominated, and the bluer colors faded faster. This color evolution is a telltale sign of a kilonova, and kilonovas can only come from neutron star mergers.”
An analysis of the event revealed several more interesting facts. For example, tracking the event to a host galaxy 1.1 billion light-years away revealed a young galaxy that is still in the process of star formation.
This is very different from the old, dead, non-star-forming galaxy from which the 2017 collision emerged. This means that the search for kilonova events may need to be extended to a wider range of galaxy types.
And, as we saw in the 2017 merger, neutron star mergers are responsible for creating heavy elements like gold and platinum.
A team of scientists simulated the emission of GRB211211A and found that the explosion generated heavy elements about 1,000 times the mass of the Earth.
As to the reason why this event was so varied in duration, we do not know. actually don’t know yet. Everything about it, except for the gamma-ray burst, matches the neutron star merger profile, which scientists say opens up some incredibly interesting possibilities.
“It was a wonderful gamma-ray burst. expect the merge to last more than two seconds. Somehow this jet powered the jet for almost a full minute.
Perhaps this behavior can be explained by a long-lived neutron star, but we cannot rule out that what we saw was a neutron star being torn apart by a black hole, says astrophysicist Benjamin Gompertz from the University of Birmingham in the UK.
“Learning more of these events will help us determine the correct answer and the detailed information we received from GRB 211211A will be invaluable to this interpretation.”
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