February 22, 2024

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These massive neutron stars exist for less than the blink of an eye: ScienceAlert

These massive neutron stars exist for less than the blink of an eye: ScienceAlert

Not much can be done in a few hundred thousandths of a second. However, for neutron stars seen in the flashes of two gamma-ray bursts, that’s more than enough time to teach us a thing or two about life, death, and birth. black holes.

By sifting through archives of high-energy flashes in the night sky, astronomers recently discovered patterns in the oscillations of light left by two different groups of colliding stars, marking a pause in their journey from a super-dense object to an infinite hole of darkness.

This pause — somewhere between 10 and 300 milliseconds — is technically equivalent to two very large, newly formed neutron stars, which researchers believe are spinning fast enough to briefly halt their inevitable fates as black holes.

“We know that short GRBs form when orbiting neutron stars collide together, and we know that they eventually collapse into Black holeHowever, the exact sequence of events is not well understood. Says Cole Miller, astronomer at the University of Maryland, College Park (UMCP) in the United States.

“We found these gamma-ray patterns in two bursts that Compton observed in the early 1990s.”

For nearly 30 years, it has been Compton Gamma Ray Observatory It circled the Earth and collected X-ray and gamma-ray luminosities spilled from distant cataclysmic events. This archive contains high-energy photons A collection of data about things like Neutron stars collide, which release powerful pulses of radiation known as gamma-ray bursts.

Neutron stars are the true monsters of the universe. It packs twice the mass of our Sun into an area of ​​space roughly the size of a small city. Not only that he does Strange things matterBy forcing electrons to form protons to turn them into a dense dust of neutrons, it can generate magnetic fields unlike anything else in the universe.

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Spinning in high spin, these fields can accelerate particles to ridiculously high speeds, forming a polar Jets that seem to “pulse” Like supercharged beacons.

Neutron stars form when more ordinary stars (about 8 to 30 times the mass of our Sun) burn up their last fuel, leaving a core of about 1.1 to 2.3 solar masses, too cool to resist the pressure of its gravity.

Add a little more mass — like two neutron stars crammed together — and not even the faint vibration of its quantum fields can resist the urge of gravity to crush the living physics out of the dead star. From a dense mass of particles we get, well, whatever indescribable horror it is that this is the heart of a black hole.

The basic theory of operation is very clear, Set general boundaries About how heavy a neutron star It could be before it collapses. For non-rotating balls of cold matter, this upper limit is just under three solar masses, but it also points to complications that might make the journey from the neutron star to the black hole less straightforward.

For example, earlier last year Physicists announce the detection of a gamma-ray burst called GRB 180618A, discovered in 2018. In the afterglow of the explosion, they detect the signature of a magnetically charged neutron star called a magneticone with a mass close to that of the two colliding stars.

Barely a day later, this heavyweight neutron star is no more, no doubt succumbing to its extraordinary mass and transforming into something not even light can escape.

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How it managed to resist gravity for as long as it did is a mystery, although its magnetic fields may have played a role.

These two new discoveries could also provide some clues.

A more accurate term for the pattern observed in the gamma-ray bursts recorded by Compton in the early 1990s is a Quasi-periodic oscillation. The mix of frequencies that go up and down in the signal can be decoded to describe the final moments of massive objects as they orbit each other and then collide.

From what the researchers can tell, each of the collisions produced an object about 20 percent larger than The current heavyweight record holder Neutron star – a pulsar Calculated to be 2.14 times the mass of our sun. It was also twice the diameter of a typical neutron star.

Interestingly, the objects were spinning at an extraordinary rate of approximately 78,000 times per minute, much faster than the speed of A pulsar bearing the record J1748-2446adwhich only runs 707 cycles per second.

The few cycles each neutron star has managed in its short split-second lifetime could have been powered by enough angular momentum to withstand its own gravitational implosion.

How this might be applied to other neutron star mergers, which further blur the boundaries of stellar collapse and black hole generation, is a question for future research.

This research has been published in nature.