Colliding neutron stars hint at new physics that could explain dark matter

Colliding neutron stars hint at new physics that could explain dark matter

An illustration of two neutron stars colliding and merging to create a kilonova blast that new be taught indicates might perhaps perhaps additionally merely be a supreme sphere.
(Relate credit: Robin Dienel/Carnegie Establishment for Science)

The collision of two neutron stars round 130 million light-years from Earth, and the strange physics this merger created, might perhaps perhaps additionally merely own shed new light on dark matter.

New be taught conducted by Washington College physicist Bhupal Dev suggests the neutron megastar merger, detected here on Earth as the gravitational wave model GW170817, could back station constraints on hypothetical particles known as “axions,” one in every of the leading candidates for dark matter.

Axions own never been straight detected, but they look in many units that prolong physics previous the so-known as In vogue Mannequin of particle physics, which is our present most efficient description of subatomic particles and how they engage with each and each more than a few.

Related: What happens when neutron stars collide? Astronomers might perhaps perhaps additionally merely sooner or later know

Dark matter is this kind of field for scientists in consequence of it would no longer engage with light, which implies it’s effectively invisible to our eyes. Dark matter also reveals an obvious lack of interplay with more than a few forces just like the electromagnetic power. Total, in consequence of of these unfamiliar features, dark matter can no longer be made up of electrons, protons and neutrons, the substances of customary matter that comprise stars, planets, our bodies and all the pieces round us on a day-to-day foundation. 

This thriller is further compounded by the true fact that the day after day stuff we’re mindful of and which is contained within the In vogue Mannequin accounts for upright 15% of the total matter within the universe.

“We now own stunning motive to suspect that new physics previous the customary model might perhaps perhaps additionally merely be lurking upright all the top device thru the corner,” Dev stated in a statement. “Wrong astrophysical environments, like neutron megastar mergers, provide a new window of opportunity in our quest for dark sector particles like axions, which could safe the indispensable to understanding the missing 85% of your whole matter within the universe.”

Are axions hiding neutron megastar wreckage?

Neutron stars are born when huge stars use their gasoline affords obligatory for inner nuclear fusion and could now no longer make stronger themselves in opposition to the inward push of their very luxuriate in gravity. As this cosmic balancing act that has existed for millions of years ends, a megastar’s outer layers are thrown away in a big supernova explosion.

This leaves within the motivate of a collapsed stellar core with the mass of the sun filled proper into a width of round 12 miles (20 kilometers). That’s a neutron megastar, named as equivalent to a consequence of it be stuffed with neutron-rich matter. Neutron stars are so dense that if a teaspoon of it had been scooped up and introduced to Earth, it would weigh round 10 million tons. That’s about 30 times as heavy as the Empire State Building.

These neutron stars occupy no longer continuously exist in isolation; in most cases, they swirl round a fellow neutron megastar companion. As these neutron stars orbit round each and each more than a few in this kind of so-known as neutron megastar binary, they create ripples in spacetime known as gravitational waves. As these spacetime ripples radiate outward, they raise angular momentum a ways off from the binary, causing its constituent stellar remnants to plot tighter together. This continues till the neutron stars’ gravity takes over and causes them to slam together and merge.

Unsurprisingly, given the intense nature of neutron stars, a collision between two such stellar remnants spurs tumultuous kinds of physics that are no longer viewed wherever else within the universe. Truly, scientists already mediate neutron megastar mergers are the handiest environments violent sufficient to forge features heavier than iron, like gold and silver, that even the boiling hearts of huge stars can no longer create. 

Here is feasible in consequence of neutron megastar collisions spray out matter rich in free neutrons, particles customarily handiest chanced on locked up in atomic nuclei alongside protons.

These neutrons can thus be swallowed by atomic nuclei within the dilemma, a phenomenon known as the “rapid-capture path of” or “r-path of.” This outcomes within the creation of unstable, huge atomic nuclei that at final decay to create lighter features like gold. This decay also produces light that astronomers locate as a kilonova from our vantage point here on Earth.

The merger also kinds a transient-lived, dense remnant of the two neutron stars that rapid collapses to birth a dusky gap. 

“The remnant will get essential hotter than the individual stars for approximately a 2nd earlier than settling down proper into a greater neutron megastar or a dusky gap, reckoning on the initial tons,” Dev explained. Dev thinks this means the remnant is the appropriate production point for strange particles like axions.

An illustration of the Fermi dwelling telescope detecting gamma rays (γ) straight from neutron megastar mergers and from the decay of strange particles they create. (Relate credit: P. S. Bhupal Dev, et al, 2024)

These particles could destroy out the location of the neutron megastar merger and decay into more than a few particles, including photons, which could be particles of sunshine. Dev and colleagues mediate the decay of these fugitive particles affords upward thrust to a selected electromagnetic model that could be picked up by gamma-ray telescopes, equivalent to NASA’s Fermi dwelling telescope.

The team thinks this means Fermi and future gamma-ray detecting instruments could point of curiosity on neutron megastar collisions to obtain data that can give a take to scientists’ understanding of axions and the same particles. 

This could at within the discovery of the particles that comprise dark matter, fixing one in every of the most pressing questions in cosmology: What is the universe’s “missing matter” fabricated from?

The team’s be taught used to be published on March 5 within the journal Bodily Evaluate Letters.

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Robert Lea is a science journalist within the U.K. whose articles were published in Physics World, New Scientist, Astronomy Journal, All About Home, Newsweek and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science level in physics and astronomy from the U.K.’s Birth College. Adjust to him on Twitter @sciencef1rst.

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