A pair of black holes have been discovered that are closer together than any pair previously observed in multiple wavelengths, a new report has revealed. They are in the heart of a galactic merger, UGC 4211, which has an active galactic nucleus, meaning its central black hole heats up the surrounding gas. When astronomers viewed the galaxy using the Atacama Large Millimeter/ Submillimeter Array (ALMA), however, they found not one, but two black holes just 750 lightyears apart. The find led to an observing campaign using telescopes across the electromagnetic spectrum.
“Each wavelength [reveals] a different part of the story,” says Ezequiel Treister from Universidad Católica de Chile, who took part in the research. “While ground-based optical imaging showed us the whole merging galaxy, Hubble showed us the nuclear regions at high resolutions. X-ray observations revealed that there was at least one active galactic nucleus in the system. All of these data together have given us a clearer picture of how galaxies such as our own turned out to be the way they are, and what they will become in the future.” www.almaobservatory.org