If you thought one black hole was scary, be very afraid,
because triple black-hole mergers are a real possibility in the universe,
according to a new supercomputer calculation.
Astrophysicists used a computer model to predict what would
happen if several black holes were to orbit each other. Often the trio would merge
into one giant black hole.
"In our simulations we see three possibilities,"
said Carlos Lousto of the Rochester Institute of Technology's Center for
Computational Relativity and Gravitation, who built the model with colleagues
Manuela Campanelli and Yosef Zlochower. "They can mesh together into one
big black hole, or two can mesh while the third orbits around in a very
elliptical orbit. And a third possibility is that all three fly apart."
Though it sounds bizarre, a triple black hole merger isn't
so far-fetched.
"Interestingly enough, at the beginning of last year,
astronomers found the first
triple quasar in the sky," Lousto told SPACE.com. "That could be
the first observed supermassive black hole triplet."
Quasars are extremely bright, faraway objects that
scientists think are powered by giant black holes at the cores of galaxies. A
team led by Caltech astronomer George Djorgovski used the W.M. Keck Observatory
on Mauna Kea, Hawaii, to observe a system of three quasars
about 10.5 billion light-years from Earth.
Lousto said this trio would probably collide eventually,
though they are far enough apart it would likely take longer than the current
age of the universe.
The merger of three black holes would be one of the most
energetic events in the universe, releasing tons of energy in the form of gravitational
waves, or warps in space-time.
So far, scientists have been unable to detect gravitational
waves, which are predicted by Einstein's General Relativity. Physicists hope
that may change soon when the first sets of data are analyzed from the
ground-based detector known as the Laser Interferometer Gravitational Wave
Observatory (LIGO)
and the future NASA/European Space Agency space mission Laser Interferometer
Space Antenna (LISA).
"We really hope we can detect gravitational
waves," Lousto said. "That's why our simulations are important. We
need a model to predict what we would see. It tells the people who do those
experiments what kind of signature is characteristic of black holes."
The scientists' model simulates the simplest case of a black
hole triplet: three non-spinning black holes of equal masses. They plan to
expand their models to include more complex systems.
Even their basic models were very computationally expensive
and took their giant supercomputer two weeks, running 24 hours a day, to
complete.
The researchers will detail their findings in the May issue
of the journal Physical Review D. The team is also set to present their
simulations at the annual meeting of the American Physical Society in St. Louis
on April 14.
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