Deep in space, some of the universe’s most dramatic events unfold when two extreme objects—like a black hole and a neutron star—spiral together and collide.
Using powerful supercomputers, scientists at Caltech have now simulated what happens in these rare and violent cosmic crashes, revealing starquakes, monster shockwaves, and brief, brilliant signals of light that may soon be spotted from Earth.
Neutron stars are incredibly dense remains of exploded stars, and black holes are even more extreme, with gravity so strong that not even light can escape.
Sometimes these two objects orbit each other until the black hole eventually swallows the neutron star whole.
The Caltech team, led by astrophysicist Elias Most, wanted to know what happens in the final seconds before this cosmic gulp.
Their first simulation showed that just before being consumed, the neutron star experiences massive quakes—its crust cracking under the tidal forces of the black hole’s gravity.
These quakes are like space earthquakes, shaking the neutron star and disturbing its magnetic field.
This motion produces magnetic ripples called Alfvén waves, which turn into powerful blast waves. According to the simulation, these could generate a flash of radio waves—something telescopes might be able to detect as a fast radio burst.
Most describes the effect as hearing a star crack, comparing the movement of the magnetic field to shaking a whip.
“Before, people thought a neutron star might crack open,” he says, “but now we see that it might also make a sound we can catch—like a cosmic signal.”
In a second study, the team simulated what happens as the neutron star is finally devoured. The star’s magnetic waves steepen and break into monster shock waves—the strongest kind of shock waves predicted in the universe.
These waves produce another blast of energy that could be seen as a separate radio burst just moments after the first. The sequence of signals could help astronomers detect and identify these rare events in real time.
Even after the neutron star is gone, the story isn’t over. The black hole is left spinning and trying to rid itself of the star’s powerful magnetic field. This leads to the formation of a “black hole pulsar,” a short-lived but exotic object that mimics the behavior of a pulsar—flashing beams of energy as it spins.
Although this state lasts less than a second, it could produce bursts of X-rays or even higher-energy gamma rays, which would give astronomers another clue that a neutron star-black hole collision has just taken place.
Thanks to the raw computing power of modern supercomputers—especially those using advanced graphics processors—researchers like Most and his colleagues can now model the mind-bending physics of these events in full detail.
Their simulations are helping scientists prepare to spot these collisions using gravitational wave detectors like LIGO, paired with telescopes that scan the sky for bursts of light.
These cosmic smashups may be brief, but their signals could light the path to understanding some of the universe’s most extreme phenomena.
https://youtu.be/684Ie6uONus
