Thursday, February 2

Neutron star collision creates colossal, paradigm-shifting flash | Digital Trends Spanish


Some of the most dramatic events in the universe are gamma-ray bursts (GRBs), short pulses of light so bright they can be seen from billions of light-years away. The researchers divide these events into short GRBs that last a few seconds and long GRBs that last up to a minute. For a long time, researchers thought that all long gamma-ray bursts were caused by the collapse of massive stars. But now new research suggests that some long GRBs could be caused by the merger of two neutron stars.

A neutron star is the dense core left behind after a huge star collapses, and is one of the densest objects in the universe, second only to black holes. Neutron stars are very small, about 6 miles across, but they are more massive than the entire sun. So when two neutron stars collide and merge into each other, the result is explosive. The merger of two neutron stars is called a kilonova, a rare event that produces a large flash of light and is known to produce short GRBs.

This artist’s impression shows a kilonova produced by two colliding neutron stars. While studying the aftermath of a long gamma-ray burst (GRB), two independent teams of astronomers using a large number of telescopes in space and on Earth, including the Gemini North telescope in Hawaii and the Gemini South telescope in Chile, They have discovered the unexpected characteristics of a kilonova, the colossal explosion caused by the collision of neutron stars. NOIR Lab/NSF/AURA/J. da Silva/Spaceengine

But when two teams of scientists investigated a newly identified GRB that lasted 50 seconds, putting it well into the long GRB classification, they discovered that it was not caused by a massive star collapse, but rather by a neutron star merger.

“This event is unlike anything we’ve seen before a long gamma-ray burst,” lead investigator Jillian Rastinejad of Northwestern University said in a paper. release. “Its gamma rays resemble those of the outbursts produced by the collapse of massive stars. Since all other confirmed neutron star mergers we have observed have been accompanied by bursts lasting less than two seconds, we had every reason to expect that this 50-second GRB was created by the collapse of a massive star. This event represents an exciting paradigm shift for gamma-ray burst astronomy.”

This means that the causes of GRBs must be more complex than previously thought. If neutron star mergers can trigger long and short GRBs, there must be something about neutron stars or GRBs that has not yet been understood.

“When you put two neutron stars together, there really isn’t a lot of mass there,” explained co-author Wen-fai Fong. “Some mass builds up and then powers up a very short duration burst. In the case of massive star collapses, which traditionally fuel longer gamma-ray bursts, there is a longer feeding time.”

The research can also be used to help find more elusive kilonova events to study by tracking long and short GRBs.

“This discovery is a stark reminder that the Universe is never fully resolved,” said Rastinejad. “Astronomers often take for granted that the origins of GRBs can be identified by the duration of the GRBs, but this discovery shows us that there is still much more to understand about these incredible events.”

The research is published in the journal Nature.

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