Astronomers have discovered a mysterious cosmic object that could be the lightest black hole, the heaviest neutron star ever discovered, or something completely new to science.
The unknown object, discovered 40,000 light-years away inside a dense ball of stars called NGC 1851, was detected by the fast flashes of its orbiting companion — a rotating neutron star known as a pulsar that sweeps out a beam of light once every 6 milliseconds. .
According to the researchers, the new entity falls within the historical “collective gap” between them black holes And neutron stars, which means it could be one or the other. The researchers published their findings on January 18 in the journal Sciences.
“The prospect as to the nature of the companion is exciting,” said lead author Ben StubbersProfessor of Astrophysics at the University of Manchester, United Kingdom. He said in a statement. “The pulsating black hole system will be an important target for testing theories of gravity and the heavy neutron star will provide new insights into nuclear physics at very high densities.”
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Both black holes and neutron stars are stellar corpses, left behind after massive stars end their lives in violent explosions called supernovas. Although they are born the same way, these two types of objects can have vastly different masses: supermassive black holes can It weighs as much as billions of sunsWhile neutron stars rarely become heavier than about three solar masses. But the lightest black holes and the heaviest neutron stars can look very similar from a distance.
For most of the history of astronomy, scientists have only been able to detect neutron stars twice the mass of the Sun and light black holes five solar masses, leaving everything in between a mystery. The gap between the two, known as the mass divide, was finally crossed in 2019, when Laser Interferometer Gravitational-Wave Observatory (LIGO) Ripples have been detected in spacetime that indicate the presence of a light black hole or a heavy neutron star located somewhere between the two. However, detection of objects filling mass gaps by conventional light-based telescopes has remained elusive.
To discover the new object, astronomers used the MeerKAT radio telescope in South Africa to survey the globular cluster NGC 1851, a crowded mass of stars packed so tightly that cosmic furnaces might knock each other out of their orbits and even collide.
Faint radio pulses repeating 170 times per second drew astronomers’ attention to the pulsar, and by noting subtle changes in its highly regular “signs,” scientists mapped its orbital motion. This revealed that the pulsar was in a binary system, orbiting an object with a mass of approximately 3.9 solar masses, an explosion in the middle of the mass gap.
It is unclear what this object could be – the most massive neutron star known, the lightest black hole, or the crust of an exotic star that has not yet been described. But the researchers said examining it further could help them test our current theories about matter.
“We’re not finished with this system yet,” co-author Arunima DuttaThe doctoral student at the Max Planck Institute for Radio Astronomy in Bonn, Germany, said in the statement. “Revealing the true nature of the companion will be a turning point in our understanding of neutron stars, black holes, and whatever else might be lurking in the black hole’s mass gap.”