Two supermassive black holes, very close to each other, have been found by astronomers

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Two supermassive black holes have been spotted feeding on cosmic material when two galaxies merge in distant space – the closest black hole collisions astronomers have ever observed.

Astronomers discovered the pair while using the Atacama Large Millimeter/Submillimeter Array of Telescopes, or ALMA, in the Atacama Desert of northern Chile, to observe two merged galaxies about 500 million light-years from Earth.

The two black holes were growing side by side near the center of the merged galaxy. They met when their host galaxies, known as UGC 4211, collided.

One is 200 million times the mass of our Sun, and the other is 125 million times the mass of our Sun.

While the black holes themselves are not directly visible, they were both surrounded by bright clusters of stars and warm, glowing gas — all pulled in by the holes’ gravity.

Over time, they will begin to orbit each other, eventually colliding with each other and creating a single black hole.

Observed across multiple wavelengths of light, the black holes are the closest together scientists have ever seen — only about 750 light-years away, which is relatively close in astronomical terms.

The results were shared at the 241st meeting American Astronomical Society Held this week in Seattle, and published on Monday in the Astrophysical Journal Letters.

The distance between black holes is “fairly close to the limit that we can detect, which is why this is so exciting,” said study co-author Chiara Mingarelli, an associate research scientist at the Center for Computational Astrophysics in New York City. , in the current situation.

Galaxy mergers are more common in the distant universe, which makes them difficult to see with ground-based telescopes. But ALMA’s sensitivity was able to observe their active galactic nuclei — the bright, compact regions in galaxies where matter orbits black holes. Astronomers were surprised to find, rather than a single black hole, a binary pair of black holes feeding on gas and dust from galactic mergers.

“Our study has identified one of the closest pairs of black holes to galaxy mergers, and because we know that galaxy mergers are more common in the distant universe, these black hole binaries may also be more common than previously thought,” lead study author Michael Koss, senior research scientist at The Eureka Institute for Scientific Research in Oakland, Calif., in a statement.

“What we just studied is a source that is in the very last stage of the collision, so what we’re seeing foreshadows this merger and also gives us insight into the relationship between black holes that merge, grow and eventually produce gravitational waves,” Koss said. .

If pairs of black holes — as well as the merging of galaxies that led to their creation — are more common in the universe than previously thought, it could have implications for future gravitational-wave research. Gravitational waves, or ripples in space-time, are created when black holes collide.

It would take a few hundred million years for this particular pair of black holes to collide, but the insights gained from this observation can help scientists better estimate how many pairs of black holes come close to colliding in the universe.

Study co-author Ezequiel Traister, an astronomer at Universidad Católica de Chile in Santiago, Chile, said in a statement. “If this is the case, then in the near future we will be observing repeated gravitational wave events caused by the merger of these objects across the universe.”

Space telescopes such as Hubble and the Chandra X-ray Observatory and ground-based telescopes such as the European Southern Observatory’s Very Large Telescope, also located in the Atacama Desert, and the WM Keck Telescope in Hawaii have also observed UGC 4211 through different wavelengths of light to provide a more detailed overview and distinction of black holes.

“Each wavelength tells a different part of the story,” Traister said. “All of this data together has given us a clearer picture of how galaxies like our own turned out to be what they are, and what they will become in the future.”

Understanding more about the final stages of galaxy mergers could provide more insight into what will happen when our Milky Way galaxy collides with the Andromeda galaxy in about 4.5 billion years.