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March 1, 2025

New theory suggests star mergers produce universe's highest-energy particles

A new paper by NYU physicist Glennys Farrar provides a tool for understanding the most cataclysmic events of the universe: two neutron stars merging to form a black hole. In the above illustration, two neutron stars are on the verge of colliding. Credit: NASA's Goddard Space Flight Center.
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A new paper by NYU physicist Glennys Farrar provides a tool for understanding the most cataclysmic events of the universe: two neutron stars merging to form a black hole. In the above illustration, two neutron stars are on the verge of colliding. Credit: NASA's Goddard Space Flight Center.

Ultrahigh Energy Cosmic Rays are the highest-energy particles in the universe, whose energies are more than a million times what can be achieved by humans. But while the existence of UHECRs has been known for 60 years, researchers have not succeeded in formulating a satisfactory explanation for their origin that explains all the observations.

But a new theory introduced by New York University physicist Glennys Farrar provides a viable and testable explanation for how UHECRs are created.

"After six decades of effort, the origin of the mysterious highest-energy particles in the universe may finally have been identified," says Farrar, a Collegiate Professor of Âé¶¹ÒùÔºics and Julius Silver, Rosalind S. Silver, and Enid Silver Winslow Professor at NYU. "This insight gives a new tool for understanding the most cataclysmic events of the universe: two merging to form a black hole, which is the process responsible for the creation of many precious or exotic elements, including gold, platinum, uranium, iodine, and xenon."

The , which appears in the journal Âé¶¹ÒùÔºical Review Letters, proposes that UHECRs are accelerated in the turbulent magnetic outflows of Binary Neutron Star mergers—spewed out from the merger remnant, prior to formation of the final black hole. The process simultaneously generates powerful gravitational waves—some already detected by scientists at the LIGO-Virgo collaboration.

These images show the merger of two neutron stars recently simulated using a new supercomputer model. Redder colors indicate lower densities. Green and white ribbons and lines represent magnetic fields. The orbiting neutron stars rapidly lose energy by emitting gravitational waves and merge after about three orbits, or in less than 8 milliseconds. The merger amplifies and scrambles the merged magnetic field. A black hole forms and the magnetic field becomes more organized, eventually producing structures capable of supporting the jets that power short gamma-ray bursts. Credit: NASA/AEI/ZIB/M. Koppitz and L. Rezzolla.
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These images show the merger of two neutron stars recently simulated using a new supercomputer model. Redder colors indicate lower densities. Green and white ribbons and lines represent magnetic fields. The orbiting neutron stars rapidly lose energy by emitting gravitational waves and merge after about three orbits, or in less than 8 milliseconds. The merger amplifies and scrambles the merged magnetic field. A black hole forms and the magnetic field becomes more organized, eventually producing structures capable of supporting the jets that power short gamma-ray bursts. Credit: NASA/AEI/ZIB/M. Koppitz and L. Rezzolla.

Farrar's Âé¶¹ÒùÔºical Review Letters proposal explains, for the first time, two of the most mysterious features of UHECRs: the tight correlation between a UHECR's energy and its and the extraordinary energy of a handful of the very highest energy events.

Stemming from Farrar's analysis are two consequences that can provide experimental validation in future work:

More information: Glennys R. Farrar, Binary Neutron Star Mergers as the Source of the Highest Energy Cosmic Rays, Âé¶¹ÒùÔºical Review Letters (2025).

Journal information: Âé¶¹ÒùÔºical Review Letters

Provided by New York University

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A new theory proposes that Ultrahigh Energy Cosmic Rays (UHECRs) are generated during the mergers of binary neutron stars, which form black holes. This process involves turbulent magnetic outflows that accelerate UHECRs and produce gravitational waves. The theory explains the correlation between UHECR energy and electric charge and suggests that the highest energy UHECRs originate from rare elements, with potential experimental validation through associated high-energy neutrinos and gravitational waves.

This summary was automatically generated using LLM.