by Some of the universe’s most energetic and mysterious light shows, long gamma-ray bursts, may be generated after dense, dead stars collide to form infant black holes surrounded by a natal disk of gas and dust.
This is the conclusion of a team of researchers who used computer simulations to show when neutron stars – dense, very dead stars when massive stars run out of nuclear fuel – collide and merge. gamma-ray burst it can be sent along the event jets and energetic particle winds.
These results could help astronomers explain the existence of strange farts gamma ray explosions that cannot be linked to the collapse of massive stars that can give birth to stellar mass as well as create neutron stars black holes.
“Our results, which connect observations with fundamental physics, have resolved many unsolved mysteries in the field of gamma-ray bursts,” said Ore Gottlieb, lead author of the research and a scientist at the Institute. Center for Computational Astrophysics (CCA), said in a statement. “For the first time, we can look at gamma-ray burst observations and know what happened before the black hole formed.”
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Solving a long gamma-ray burst puzzle
Gamma-ray bursts were first observed in the late 1960s, and since then, they have presented an enduring puzzle to scientists as the exact mechanism that creates these bursts of high-energy light remains a mystery.
The picture is further complicated by the fact that there are two distinct populations of gamma-ray bursts: short-duration bursts of less than a second and long-duration bursts, lasting longer than 10 seconds.
First, physicists linked short bursts of gamma-rays to jets that burst out in the ocean neutron star compound, which generates flashes of light also known kilowatt and creating so-called “hypermassive neutron stars” that rapidly collapse themselves to give birth to black holes. Long gamma-ray bursts, on the other hand, have been attributed to jets of matter launched when rotating giant stars collapsed to give birth to black holes or neutron stars.
However, in 2022, astronomers detected two long gamma-ray bursts that had little to do with other patterns of radiation bursts of this type. So these explosions could not have been caused by the collapse of a massive star, the scientists said. This is what first led experts to speculate that cosmic collisions could create long gamma-ray bursts under certain circumstances.
Gottlieb and his colleagues have spent months running sophisticated simulations with the Flatiron Institute’s supercomputers to see if such a hypothesis was true, and indeed could trigger a long burst of gamma rays.
The simulations begin with two compact objects closely orbiting each other, then spiraling together, colliding and merging. After the merger, the event sends out jets of material at sub-light speeds. The team then saw these jets in the simulation as they traveled far away from the center of the merger site.
Combining this model with data collected in astronomical observations, Gottlieb and his colleagues devised a unified model for gamma-ray bursts, showing that strange long examples of gamma-ray bursts could be created after neutron star mergers. This would happen, they say, because the resulting composite body is surrounded by a rotating disk of magnetically charged remnant material. This ring of material could technically send out a long burst of gamma rays.
Interestingly, the model could help scientists determine what the system that sent those gamma-ray bursts looked like before the merger.
“If we see a long gamma-ray burst like the ones observed in 2022, we now know that it is coming from a black hole with a massive disk,” Gottlieb said. “Knowing that there is a massive disk, we can now work out the ratio of the masses of the two parent objects because their mass ratio is related to the properties of the disk. For example, the merger of neutron stars will inevitably imbalance-mass involved. produce a long-duration gamma-ray burst.”
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The team’s model doesn’t just apply to long gamma-ray bursts either. It could be used to better understand the process behind the launch of short gamma-ray bursts. Gottlieband and team’s model may be suggesting that these potentially shorter bursts of high-energy radiation could come from smaller disks of material around black holes.
Or, alternatively, short gamma-ray bursts could emerge from unstable hypermassive neutron stars before rapidly collapsing into natal black holes, the team says. Using the model in this way will require fine-tuning and require more gamma-ray burst observational data. , which could be coming when the Vera C. Rubin Observatory start looking in early 2025.
“As we obtain more observations of gamma-ray bursts at different pulse durations, we will be able to better explore the central engines that power these extreme events,” concluded Gottlieb.
The research was published on 29 November i The Astrophysical Journal Letters.
