Probing the mysteries of neutron stars with a surprising earthly analog

Since the discovery of neutron stars, researchers have exploited their unusual properties to probe the universe. The ultra-dense remnants of stellar explosions, neutron stars pack more mass than the Sun into balls the width of San Francisco. A cup of this star’s material would weigh as much as Mount Everest.

These strange objects alert us to distant disturbances in the fabric of spacetime, teach us about the formation of elements, and show us how gravity and particle physics work in some of the universe’s most extreme conditions. may unlock the secrets of

“They are at the heart of many unanswered questions in astronomy and astrophysics,” says astrophysicist Vanessa Graeber of the Institute of Space Science in Barcelona.

But to accurately interpret some of the neutron star’s signals, researchers first need to understand what’s going on inside. They have a hunch, but experimenting directly with a neutron star is out of the question. Scientists therefore need another way to test their theories. The behavior of matter in such ultra-dense objects is so complex that even computer simulations cannot keep up with it. But researchers think they may have found a solution in a terrestrial analogue.

The interior of a young neutron star can reach temperatures in the millions of degrees, but neutrons are considered “cold” according to important energy measures. Physicists believe this is a property that can be exploited to study the inner workings of neutron stars. Instead of looking at the sky, researchers are looking at ultra-cold clouds of atoms created in laboratories on Earth. And it may help finally answer long-standing questions about these mysterious objects.

strangeness of the universe

The existence of a neutron star was first proposed two years later, in 1934. discover When astronomers Walter Baade and Fritz Zwicky studied the neutron itself, wondered What if after a supernova explosion an object made entirely of neutrons might remain? They didn’t get all the details exactly right, but their general ideas are now widely accepted.

Stars power themselves by fusing the nuclei of lighter atoms into the nuclei of heavier atoms. But when the star runs out of those light atoms, nuclear fusion stops and there is no outward pressure to counteract the inward gravitational pull. The core collapses and the outer layers of the star surge inward. When this layer collides with the dense core, it bounces back and explodes outward, creating a supernova. The dense core that remains after that is a neutron star.

It wasn’t until the 1960s that Zwicky and Barde’s hypothetical neutron star was finally detected. Radio astronomer Jocelyn Bell Burnell was working as a graduate student at the University of Cambridge when she noticed a strange, regularly pulsed radio signal from space.she was detecting something never seen before: A special kind of neutron star, called a pulsar, that emits radiation at regular intervals while rotating like a lighthouse. (Not Bell Burnell, but her advisor and observatory director later won the Nobel Prize for this discovery.)

Since then, thousands of neutron stars have been detected. Neutron stars, some of the densest and most pressure-heavy objects in the universe, may help us learn what happens to matter at ultra-high densities. Understanding their structures and the behavior of the neutronic matter that makes them up is of paramount importance to physicists.

Scientists already know that the neutrons, protons and other particles that make up a neutron star are arranged differently depending on where they are in the star. In certain sections, they are stuck together like water molecules in a block of ice. In other cases they flow and swirl like frictionless fluids. But physicists aren’t sure exactly where transitions occur and how different phases of matter behave.

The super-dense stars born from the core fireball seem, at first glance, to have little in common with the sparse clouds of ultra-cold particles. But they can share at least one useful property. Both are below a threshold, known as the Fermi temperature, which is calculated on the basis of which materials each system is composed of. Systems well above this temperature operate primarily according to the laws of classical physics. Well below that, its behavior is governed by quantum mechanics. Christopher Pesick, a theoretical physicist at the Niels Bohr Institute in Copenhagen and co-author of the earlier paper, said that certain ultracold gases and neutron star matter could both be well below the Fermi temperature, and that As a result, it is said that it may have the same effect. Overview of Neutron Stars In the 1975 Nuclear Science Annual Reviewe.

Substances below the Fermi temperature can obey surprisingly universal laws. This ubiquity suggests that while neutron-star matter of millions of degrees is not easily accessible, some of its behavior can be explored by experimenting with ultra-cold gases that can be produced and manipulated in vacuum chambers in laboratory laboratories on Earth. It states that it means to be able to know.James Latimer, theoretical astrophysicist at Stony Brook University, New York, author An overview of nuclear materials science In the 2012 Nuclear and Particle Science Annual Review.

Of particular interest to Latimer is a theoretical state called unitary gas. A gas becomes unity when the radius of influence of each of its particles becomes infinite. This means that particles affect each other no matter how far apart they are. This is not possible in reality, but the cryogenic atomic clouds can get closer, and so can the matter inside the neutron star. “It’s like a single gas, but it’s not quite a single gas,” Latimer said.