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Astronomers detect a black hole swallowing a neutron star for the first time

On January 5, 2020, astrophysicists heard a bird chirping from a distant part of the universe. 900 million light-years away, the fleeting sound was unlike anything they had ever heard before. And caused by the massive ripples in spacetime — gravitational waves — that spread across the universe from 900 million light-years away, wiped out the Earth and sounded a ping. detector chick.

Then, 10 days later, they heard another similar sound. Cosmic Twins Gravitational waves send an alarm to Earth’s detectors again. chick.

After careful analysis Both signals have been identified as being caused by unprecedented extreme events in deep space. That̵

7;s a collision between a black hole and a neutron star.

clash (also known as The “mergers and acquisitions”) are detailed in a new study published in Scientific American. Astrophysical Journal Letters on Tuesday More than 1,000 scientists from the LIGO/Virgo collaboration and KAGRA are multinational efforts to Hunt for gravitational wavesThe two newly described events are named GW200105 and GW200115 for the date of their discovery. And it’s the first clear evidence of an elusive merger.

Prior to dual detection Astronomers have only found black holes merging with black holes and neutron stars merging with neutron stars.

Susan Scott, an astrophysicist at the Australian National University and member of the OzGrav and LIGO collaboration said: “We have been waiting and expecting that at some point one system will be detected.

now they have

in the last two years There is a suggestion that There may have been a collision between a neutron star and a black hole. — But there’s one thing that seems a little unusual. It’s too big to be a neutron star. and too small to be a black hole Unknown object remains a mystery This means that the GW200105 and GW200115 will go down in history.

Rory Smith, an astrophysicist at Monash University in Australia and a member of the LIGO collaboration, added: “This is the first time that a neutron star-black hole merger has been truly detected with confidence.


A quick interlude before we continue.

Black holes and neutron stars are strange objects. They are dead star objects and form at the end of the star’s life. The size of a star affects the life of a star nearing its end. If it were a tiny star (small, “about 10 times the mass of the Sun”), it would collapse into an incredibly dense “zombie star”. known as a neutron star If it’s a big star will collapse into a black hole Both are well known and well studied objects. But there are still many mysteries.

For one, we can’t see inside them. This is one of the most discussed characteristics of black holes. Their gravity is so strong that when light is pulled in – past the event horizon – it will never come back out. But scientists don’t know what’s going on in the center of a neutron star. They suspect that strange physics may be occurring within the two objects. The laws of physics seem to be broken within.

Observing an object through gravitational waves is According to Smith, they are “fossils of stars” because they can tell us about their evolutionary history and the environment in which they formed.

The chirping sound was at the center of this when LIGO, based in the US and Virgo in Italy, detected it. “Chip sounds” They are looking back on the past. Within the chirping sound is a wealth of information that can tell astrophysicists how big the colliding objects are and how they spin. This information is critical for understanding how the two objects are trapped in each other’s death dance.

“From the study of these systems We have learned a lot more about the life and death of black holes and neutron stars in these binary systems,” Scott said.

star stuff

GW200105 chirping detected January 5, 2020 and GW200115 chirping detected January 15, 2020 are similar events. But the colliding objects have slightly different properties. These stuffy scientific names are a bit confusing. So we named it Lenny (GW200105) and Carl (GW200115).

Researchers say that Lenny is the result of a black hole about nine times the mass of the Sun colliding with a neutron star about 1.9 solar masses. Karl traveled through a black hole about six times the mass of the Sun, merging with a neutron star about 1.5 times the mass of the Sun. Lenny and Karl are completely different creatures these days. The merger took place almost a billion years ago far from Earth. And a chirping sound soon reached us.

When we say “collision” or “merge” here, we’re not sure what happens when the two objects eventually merge. For a long time they had been in circles being trapped by the gravity of the other party. They finally came together. Scott describes Lenny and Karl as “Similar to Pacman,” where a black hole swallows a neutron star.


Another artistic interpretation of the merger of black holes and neutron stars with black holes stealing material from their counterparts.

LIGO-India/Soheb Mandhai

There is also the possibility that black holes “destroy” neutron stars in a process known as wave disruption. In this scenario Black holes will tear material from the surface of neutron stars and steal it. causing a disk of debris around the event horizon “That should generate an electromagnetic signal,” Scott said.

and shredded neutron stars are gold mines for astrophysicists. You cannot make a material appear in a neutron star in a laboratory and study it. So this kind of event might open a window to understand what’s going on inside it.

“By watching how Black holes pull neutron stars apart. We are beginning to learn how matter behaves in its densest state,” said Eric Thrane, an astrophysicist at Monash University and a member of the LIGO collaboration. properties

That makes Lenny and Karl the first merging black hole-neutron star. Help shed light on the most violent objects in our universe.

“These observations may one day reveal new laws of nature,” Smith said.

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