A team of international astronomers are hunting old, super-massive black holes – and they have hit the motherlode and discovered 83 previously unknown quasars.
The universe is full of super-heavy black holes, monstrous versions of the simple, everyday black hole, millions or billions of times that of our sun. These huge cosmic beasts generate gigantic gravitational effects, so you will often find super-heavy black holes hiding in the center of galaxies surrounded by billions of stars. That is exactly what happens in our own galaxy of the Milky Way.
To find them lurking in the distant parts of the universe, you need to study the light of growing gasses swirling around them. Because we cannot see a black hole, but we can see the light, we refer to these powerful light sources as "quasars." Under the eyepiece of a telescope, they may look more like stars – they are extraordinarily bright – but scientists usually believe that their light comes from gases falling in the direction of a black hole.
The Japanese team changed the ultra-powerful "Hyper Suprime-Cam," mounted on the Subaru Telescope in Hawaii, toward the darkest corners of the cosmos and looked over the sky over a five-year period. By studying the snapshots, they have been able to get potential quasar candidates out of the dark. In particular, their method of investigating populations of super-heavy black holes similar to those of the ones we see in today's universe has given us a window on their origins.
After identifying 83 potential candidates, the team used a series of international telescopes to confirm their findings. The quasars that they have picked are from the very early universe, about 13 billion light years away. In practice, this means that the researchers look at the past, at objects that take place 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 newspaper, in a press release.
Scientists are not sure how black holes are formed in the early universe, so being able to detect them so far back in time offers new avenues for exploration. In particular, the researchers discover a quasar with a much lower brightness than they had expected. The characteristics of that specific quasar, HSC J124353.93 + 010038.5, were reported in The Astrophysical Journal Letters in February.
"The quasars that we discovered will be an interesting topic for further follow-up observations with current and future facilities," said Yoshiki Matsuoka, lead investigator, in a statement.