Hanford observatory records historic collision between black hole, neutron star

(Carl Knox/OzGrav/Swinburne University Australia via AP)
This illustration provided by Carl Knox depicts a black hole, center, swallowing a neutron star, upper left. The blue lines are gravitational waves, ripples in time and space, which is how astronomers detected the merger, and orange and red areas indicate parts of the neutron star being stripped away. In a report released on Tuesday, June 29, 2021, astronomers say they have witnessed a black hole swallowing a neutron star, the most dense object in the universe, _ all in a split-second gulp.

HANFORD, Wash. — Stargazers have observed space above us for centuries, but never before have scientists confirmed a collision between a black hole and a neutron star. That changed recently when the Laser Interferometer Gravitational-Wave Observatory (LIGO) in Hanford and its twin observatory in Livingston, Louisiana detected two of these instances in January 2020.

According to a report published in ‘The Astrophysical Journal Letters’ here, the first merger between a black hole and a neutron star was detected on January 5, 2020. Gravitational waves from the collision were picked up by LIGO Livingston and the Virgo detector, which is based in Italy. However, the LIGO detector in Hanford was offline at the time of the cosmic collision.

Luckily, gravitational waves were detected again on January 15 when a 6-solar-mass black hole and a 1.5-solar-mass neutron star collided, as recognized by all three detectors.

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Based on gravitational waves, scientists determined that the collision took place 1 billion light-years from Earth. They searched the sky for a flash of light or other identifiable oddities caused by the merger. This wasn’t surprising to scientists as the black hole may have consumed the neutron star entirely, dimming any light and making this event invisible to the human eye.

“These were not events where the black holes munched on the neutron stars like the cookie monster and flung bits and pieces about. That ‘flinging about’ is what would produce light, and we don’t think that happened in these cases,” says Patrick Brady, a professor at the University of Wisconsin-Milwaukee and Spokesperson of the LIGO Scientific Collaboration.

A neutron star is a collection of closely packed neutrons that is the result of a massive supergiant star’s core collapsing. Black holes, on the other hand, are a section of spacetime with gravity so intense that nothing, including particles and light of any kind, can escape its pull.

“With this new discovery of neutron star- black hole mergers outside our galaxy, we have found the missing type of binary. We can finally begin to understand how many of these systems exist, how often they merge, and why we have not yet seen examples in the Milky Way,” says Astrid Lamberts, CNRS researcher of the Virgo collaboration at Artemis and Lagrange laboratories, in Nice.


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