Last year, astronomers saw a black hole eat a dead star for the first time, like a raven eating roadkill.
In a different part of the galaxy, they witnessed the same behaviour 10 days later.
On Tuesday, researchers in the field of gravitational astronomy published a new study detailing their newest findings, which include a discovery of the stretching and scrunching of space-time caused by some of the most catastrophic events in our galaxy.
Physicist Patrick Brady, a spokesman for the LIGO Scientific Collaboration, said, “It’s the first time we’ve really been able to detect a neutron star and black hole merging with each other anywhere in the universe,” he said.
Astronomers had long thought that black hole-nuclear star couples were possible. However, their suspicions remained unconfirmed until they came across these collisions. Discovery helps fill in knowledge about binary star systems in the universe, while also raising questions about why scientists have never spotted such a pair in our Milky Way galaxy.
This rumble has been predicted by Einstein’s theory of general relativity, and LIGO, the Laser Interferometer Gravitational-Wave Observatory, has been looking for it for more than two decades. The two observatories, one at Hanford, Wash., and the other in Livingston, La., have been unable to detect anything for years.
Both LIGO sites witnessed the long-awaited ringing of gravitational waves in September 2015.
It was the collision of two stellar-sized black holes that formed those waves, punctures in the fabric of space-time created by dying stars exploding as supernovas. The two black holes swung closer and closer to each other until they merged into a single entity.
A collision of two neutron stars, each with a mass of around a billion times that of the sun, was discovered by LIGO two years later. Astronomers have been able to identify a wide range of light particles coming from the explosion, from radio waves and X-rays to microwaves and radio waves.
The search for a neutron star orbiting a black hole has been going on for nearly half a century, but no such object has been discovered. Dr. Brady added, “So in effect, we’ve got this mystery question.” How come a neutron star-black hole system has not been observed?
Despite their distance from the Milky Way, these gravitational wave couples are now confirmed to exist. On January 5, 2020, a neutron star colliding with a black hole was detected for the first time. When the Hanford, Wash., facility was down for maintenance, the signal was picked up in Livingston, La. VIRGO, a smaller and less powerful detector in Italy, also caught a faint signal, confirming the findings of the larger detector.
Physicists were able to discover the nature of objects colliding in the remote reaches of the universe by analysing the frequency of the gravitational waves.
Both the black hole and the neutron star were between 7.4 and 10.1 times as massive as our sun, but the neutron star was far smaller. At a distance of around 900 million light-years from Earth, the collision happened.
A second black hole-nuclear star collision was identified on Jan. 15, 2020, when the Hanford site reopened. This one was a little more out of the way, though. The weight of both things has decreased. When compared to the sun’s mass, the neutron star weighed nearly 1.5 times as much as the black hole.
When two neutron stars collided in 2017, telescopes could not detect any light from the explosions. It is possible that the black holes were large enough to quickly ingest the neutron stars, limiting the risk of emission.
Max Planck Institute for Gravitational Physics head Alessandra Buonanno, who was also a member of the LIGO research team, noted that the collisions were in line with their expectations. ‘It’s hardly something you’d call surprising,’ she added.
There were no traces of the black holes ripping up neutron stars before eating them, according to astronomers. A black hole’s tidal forces on a neutron star would reveal the star’s diameter, which in turn would reveal its composition.
In the future, as more collisions are seen, patterns will begin to form and more details will be discerned.
According to Dr. Brady, “if you found a system with a smaller black hole, the tidal effects on the neutron star are greater before it merges with the black hole.” The neutron star will be shredded when it makes its final few orbits, because of this.
Dr. Brady stated that one of the lingering puzzles was why no black hole-neutron pairings had been identified in the Milky Way galaxy. ‘ Search methods may have been faulty, or the pairs may have swiftly merged and there are no more in our galaxy. It’s now “sort of the open question,” he stated.
To improve its performance, VIRGO is receiving improvements. If all goes according to plan, LIGO and VIRGO will begin observing in June of 2013. There are plans for a third LIGO detector in Japan, as well as a new one in India.