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A collision between two black holes

Avi Blizovsky

The black holes are clearly visible in the X-ray field

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For the first time, scientists were able to "see" two massive black holes merging at the center of the same galaxy. The black holes orbit each other and they will collide to create an even bigger black hole. The result will be a massive event that will release a lot of radiation and gravitational waves. In any case, this will not happen in the next few hundred million years.
The observations made by the Chandra X-ray imaging satellite show that the core of an extremely bright galaxy, NGC 6240, contains two giant black holes that are each swallowing the material around it.
This discovery shows that massive black holes can grow through mergers at the centers of galaxies.
The breakthrough was made possible by Chandra's ability to clearly see the two nuclei and measure the details of the X-rays from the center." says Günter Hassinger from the Max Planet Institute for Foreign Physics in Germany. This cosmic fingerprint is characterized by supermassive black holes - which emit strong radiation from the gas surrounding the black hole, he said.

Two black holes are going to collide with each other in hundreds of millions of years

By Warren Leary

Space / Galaxy "NGC-6240, about 400 million light-years away from Earth, was formed from a merger between two galaxies

In the photo: the galaxy "NGC-6240" as photographed by the Hubble telescope (left), and in an X-ray observation from the "Chandra" observatory

New York Times

Two huge black holes, discovered in the center of the galaxy "NGC
,” 6240 are going to collide with each other in a few hundred million years. The massive collision will cause the release of radiation and gravitational waves that may spread to the ends of the universe. The identification of the two black holes provides the first and unequivocal proof that two objects of this type can coexist in one galaxy.

"The gravity waves will propagate and create waves in the fabric of space," said Dr. Ginther Hsinger, a member of the research team that discovered the two holes, at a NASA briefing held yesterday. According to him, these waves will eventually hit the galaxy where the Earth resides and cause a tiny vibration in all existing matter, but the vibration will be too small to be felt by humans.

Singer, an astrophysicist at the "Max Planck Institute for Space Physics" located near Munich, said that in previous observations of the galaxy, only two bright radiation points were discovered in its center. However, with the help of observations conducted at "Chandra" - an observatory that uses X-rays - it was discovered that the two bright spots are actually X-rays emitted from material swallowed by a black hole, which indicated the existence of two active black holes. "This is the first time we have detected a double black hole," said astronomer Dr. Stephanie Komosa who participated in the study. "This is the result of a collision between two galaxies in the past."

NGC-6240 lies about 400 million light years from Earth. It was formed as a result of a merger between two galaxies of similar size. The diameter of each of the two black holes that were discovered is about 460 million kilometers - about the diameter of the orbit of Mars around the Sun. They orbit each other at a distance of about 3,000 light years.

According to astronomers, the merger of galaxies that created NGC-6240 hints at the future happening in the Milky Way galaxy, where Earth resides, which consists of hundreds of millions of stars. In about four billion years, astronomers believe, the Milky Way and the nearby Andromeda galaxy will collide and merge, and their black holes will melt into one. "We see our own future," said astronomer Dr. Stein Sigurdsson from the University of Pennsylvania yesterday.

According to Singer, when the merger of the galaxies takes place there will no longer be humans on Earth. By then, the sun is expected to swell to the dimensions of the Earth's orbit around it (about 300 million kilometers), and then shed its outer parts and become a small, white star.

In Singer's estimation, black hole mergers, like the one seen in NGC-6240, were common throughout the universe - every year several black holes appear in areas that can be observed from Earth. According to him, many bright objects that emit large amounts of X-rays and other types of radiation may actually be mergers of black holes.

So far, scientists have identified two types of black holes: giants with masses of millions of stars hidden in the cores of galaxies; And smaller black holes, which are the remains of large stars that have collapsed, have masses 15-3 times the mass of the Sun.

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