Astronomers said on April 6, 2021, that they’ve spotted two rare double quasars. Each pair is thought to reside in the midst of two merging galaxies in the very distant universe. Astronomers estimate that only one in 1,000 quasars is double, so finding two double quasars could be seen as lucky. The astronomers would tell you, though, that they didn’t use luck. They used a series of telescopes that led them from one step to the next, in a methodical unraveling of the mystery of which bright, apparently single quasars might actually be double. As lead researcher Yue Shen of the University of Illinois at Urbana-Champaign put it:
Finding these double quasars is like finding a needle in a haystack.
A collaboration between scientists and some of the best telescopes in the world led to new images of the double quasars. The study was published April 1, 2021, in the peer-reviewed journal Nature Astronomy.
To find the quasar pairs, astronomers pored over 3D maps from the Sloan Digital Sky Survey to find double-quasar candidates. Then they used data from the Gaia Observatory to pin down the locations. Gaia is able to detect slight jiggles in the movement of the distant ...