Lurking in the distant corners of space are 83 monster black holes that can teach us about the early days of the cosmos.
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 black hole, containing masses that are
millions or billions of times that of our sun. 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 JournalLetters.
"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.
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