A team of international astronomers have been hunting for ancient, supermassive black holes -- and they've hit the mother lode, discovering 83 previously unknown quasars.
The universe is full of supermassive black holes, monstrous versions of the humble, everyday, containing masses that are millions or billions of times that of our . These huge cosmic beasts generate mammoth gravitational effects, so you often find supermassive black holes hiding out at the center of galaxies, orbited by billions of stars. That's exactly what happens in our home galaxy of the Milky Way.
To find them lurking out in the distant parts of the universe, you need to study the light of accreting gases that swirl around them. Because we can't see a black hole, but we can see the light, we designate these powerful light sources "quasars." Down the eyepiece of a telescope they might look more like stars -- they are extremely bright -- but scientists mostly believe their light comes from gases falling toward a black hole.
The Japanese team turned the ultra-powerful Hyper Suprime-Cam, mounted to the Subaru Telescope in Hawaii, toward the cosmos' darkest corners, surveying the sky over a period of five years. By studying the snapshots, they've been able to pick potential quasar candidates out of the dark. Notably, their method of probing populations of supermassive black holes, similar in size to the ones we see in today's universe, has given us a window into their origins.
After identifying 83 potential candidates, the team used a suite of international telescopes to confirm their findings. The quasars they've plucked out are from the very early universe, about 13 billion light years away. Practically, that means the researchers are looking into the past, at objects formed less than a billion years after the Big Bang.
"It is remarkable that such massive dense objects were able to form so soon after the Big Bang," said Michael Strauss, who co-authored the paper, in a press release.
Scientists aren't sure how black holes formed in the early universe, so being able to detect them this far back in time provides new avenues of exploration. Notably, the researchers discovered a quasar with a much lower brightness than they expected. The features of that particular quasar, HSC J124353.93+010038.5, were reported in The Astrophysical Journal Letters in February.
"The quasars we discovered will be an interesting subject for further follow-up observations with current and future facilities," said lead researcher Yoshiki Matsuoka in a statement.