Signals written in elements from the early universe have revealed the oldest known merger between two galaxies, taking place less than a billion years after the Big Bang.
Researchers recently turned to the Atacama Large Millimeter Array (ALMA) telescope in Chile to look for radio emissions from a distant but very bright star-forming galaxy known as B14-65666, located about 13 billion light-years from Earth. Prior observations in the ultraviolet spectrum by the Hubble Space Telescope hinted that the galaxy contained two “clumps” of stars, the northeastern “Clump A” and the southwestern “Clump B.”
New observations using ALMA, a highly sensitive radio telescope, identified three distinctive signatures in each of the two clumps: those from carbon, oxygen and dust. (The three sources all produce distinctive signals in radio waves.) Such signals have never been found in a galaxy this old; variations between those signals told the scientists that B14-65666’s dual clusters represented two galaxies that had merged before the universe was even a billion years old, the researchers reported in a new study.