Free Astronomy Magazine July-August 2021

39 JULY-AUGUST 2021 ASTRO PUBLISHING every one thousand quasars, there is one double quasar. So finding these double quasars is like finding a needle in a haystack,” commented Yue Shen, an astronomer at the Uni- versity of Illinois and lead author of the paper announcing this discov- ery. Quasars are the intensely bright cores of distant galaxies, powered by the feeding frenzies of super- massive black holes. These energetic objects profoundly affect galaxy formation and evolution, making observations of quasar pairs in the early Universe a unique way for as- tronomers to investigate the evolu- tion of merging galaxies. Quasar pairs also provide a natural labora- tory in which to study the processes leading to the formation of binary supermassive black holes. “This truly is the first sample of dual quasars at the peak epoch of galaxy formation that we can use to probe