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Neutron stars are the remnants of supernova explosions.
They're known for their extreme density, and it's often said and written that a teaspoon of neutron star weighs as much as the combined weight of all of Earth's approximately 8 billion human beings.
The only thing denser than a neutron star is a black hole. Born from such calamity, it's not surprising thatneutron starshave other extreme properties too.
They're known for their extraordinarily powerful magnetic fields, generated by the same collapse that generates their extreme density.
Researchers are exploring a link between these magnetic fields and what happens to neutron stars when they merge. Given their powerful properties, it's no surprise that when two neutron stars (NS) merge, extremely powerful physics are involvde.
A neutron star merger is a cataclysmic event that builds up over hundreds of millions of years, though the merger—the final act—lasts only milliseconds.
When a pair of neutron stars spiral toward each other and eventually merge, it triggers a kilonova explosion and releases a short gamma-ray burst (GRB), the most energetic type of event in the Universe.
The end result of the merger is either a more massive NS or a black hole.
In an effort to understand these extraordinary events, a gamma-ray detector like NASA's Fermi satellite has to detect a GRB.
Then astrophysicists take the data from that detection, gather any other observations like gravitational waves, and piece together what happened. Despite everything researchers have learned about neutron stars, their insides are still mysterious.
It's the realm of theory over observation.
But when a pair of neutron stars is about to merge, their churning, interacting magnetic fields could be a window into their mysterious interiors. Research published in The Astrophysical Journal simulated the final few orbits of a pair of inspiralling, merging neutron stars to see what high-energy signals the orbits generated.
It's titled "Magnetosphere Evolution and Precursor-driven Electromagnetic Signals in Merging Binary Neutron Stars." The lead author is Dimitrios Skiathas, a graduate student at the University of Patras in Greece.
Skiathas is conducting research at NASA's Goddard Space Flight Center. “Just before neutron stars crash, the highly magnetized, plasma-filled regions around them, called magnetospheres, start to interact strongly.
We studied the last several orbits before the merger, when the entwined magnetic fields undergo rapid and dramatic changes, and modeled potentially observable high-energy signals,” said lead author Skiathas in a press release. The researchers used supercomputer simulations to investigate the magnetosphere interactions, and what electromagnetic signals might be emitted.
"Our simulations fully follow a representative inspiral motion, capturing the intricate magnetospheric dynamics and their impact on EM outflows," the researchers explain in their paper. The researchers used NASA's Pleiades supercomputer to simulate the merger of two NS with 1.4 solar masses each.
The primary goal was to watch the pair's magnetic fields.
Neutron stars rotate very rapidly, dozens of times per second.