Free Astronomy Magazine July-August 2021

38 JULY-AUGUST 2021 ASTRO PUBLISHING Black hole pairs found in distant merging galaxies by NOIRLab - Amanda Kocz A stronomers have discovered two pairs of quasars in the distant Universe, about 10 billion light-years from Earth. In each pair, the two quasars are separated by only about 10,000 light-years, making them closer to- gether than any other double quasars found so far away. The proximity of the quasars in each pair suggests that they are located within two merging galaxies. [International Gemini Observatory/ NOIRLab/NSF/AURA/J. da Silva] A stronomers have found two close pairs of quasars in the distant Uni- verse. Follow-up observations with Gemini North spectroscopically resolved one of the distant quasar pairs, after their discov- ery with the Hubble Space Telescope and Gaia spacecraft. These quasars are closer to- gether than any pair of quasars found so far away, providing strong evidence for the exis- tence of supermassive black hole pairs as well as crucial insight into galaxy mergers in the early Universe. The quasars in each of the two pairs are separated by just over 10,000 light- years, suggesting that they belong to two merging galaxies. Double quasars are scientifically interesting but rare objects — particularly in the most dis- tant reaches of the Universe — and these are the most distant quasars found that are so close together. We see these quasar pairs as they existed roughly 10 billion years ago. “We estimate that in the distant Universe, for