A nearby galaxy merger contains two massive black holes that appear to be the closest pair ever detected at multiple wavelengths, according to a new study.
The two galaxies, collectively known as UGC 4211, are located just 500 million light-years from Earth in the constellation of Cancer and are in the final stages of merging. Using the Atacama Large Millimeter/Submillimeter Array (ALMA), an international observatory in Chile, scientists have discovered two black holes feeding on the by-products of a galactic merger, the research team said in a statement. (will open in a new tab).
When these supermassive black holes gobble up nearby matter, they emit bright jets and winds, creating a bright active galactic nucleus that ALMA can detect. Recent observations show that the two black holes are only 750 light-years apart.
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(Image credit: ALMA (ESO/NAOJ/NRAO); M. Weiss (NRAO/AUI/NSF))
“ALMA is unique in that it can see through large columns of gas and dust and achieve very high spatial resolution to see objects very close together,” said Michael Koss, lead author of the study and senior scientist at Eureka Scientific. statement. “Our study has identified one of the closest pairs of black holes in galaxy mergers, and since we know that galaxy mergers are much more common in the distant universe, these binary black holes may also be much more common than previously thought.”
Galactic mergers in the distant universe, while common, can be difficult to observe. Thus, detecting a nearby galaxy merger such as UGC 4211 with an active pair of supermassive black holes could help detect the gravitational waves generated by these cataclysms.
“There may be many pairs of growing supermassive black holes at the centers of galaxies that we have not yet been able to identify,” said Ezequiel Treister, study co-author and astronomer at the Pontifical Catholic University of Chile. statement. “If this is the case, then in the near future we will observe frequent gravitational wave phenomena caused by mergers of these objects throughout the universe.”
To get a complete picture of UGC 4211, the researchers used data from other telescopes, including the Chandra X-ray Observatory, the Hubble Space Telescope, the Very Large Telescope, and the V.M. Keka. Together, the data provided insight into the galactic merger from multiple wavelengths.
“Each wavelength tells a different part of the story,” Traister said in a statement. “While ground-based optical images showed us the entire merging galaxy, Hubble showed us high-resolution nuclear regions. X-ray observations have shown that the system has at least one active galactic nucleus. And ALMA showed us the exact location of these two growing hungry supermassive black holes.
“All of this data together has given us a clearer picture of how galaxies like ours came to be the way they are, and the way they will be in the future,” he added.
Our Milky Way galaxy is on a collision course with another spiral galaxy called Andromeda. The collision is still in its early stages and is predicted to occur in about 4.5 billion years.
“What we have just studied is the source at the very last stage of the collision, so what we see portends that [Milky Way-Andromeda] merger, and also gives us insight into the relationship between mergers and the growth of black holes and, ultimately, the formation of gravitational waves, ”Koss said in a statement.
Their findings were published Monday (January 9) in The Astrophysical Journal Letters. (will open in a new tab); The researchers also presented the work at the 241st meeting of the American Astronomical Society, which will be held this week in Seattle and virtually.
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