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Here are four videos for you to
enjoy and share, by Vijay Varma, a Caltech Ph.D. student.
Each video shows the merger of two black holes orbiting one another.
The black holes lose orbital energy as they emit gravitational waves,
so they get closer and closer until they merge, forming one
more-massive black hole.
Most of the black
holes in these videos are spinning rapidly, and are therefore shown as
oblate spheroids with arrows indicating their spin angular momenta. A
crimson arrow at the orbital center indicates the total orbital angular
momentum of both black holes.
The gravitational
wave being generated is depicted on a plane below the orbiting black
holes, with stretching indicated by shades of red and compression
indicated by shades of blue.
Below the main
plot is a graph of the gravitational wave amplitudes of the plus and
cross polarizations.
The time scales of
each video are continually adjusted to provide 30 frames per orbit
during the inspiral-merger-ringdown phases. In real time, a single
orbit might take thousands of years initially, while the final orbit
might last only thousandths of a second. The ringdown phase begins when
the event horizons of the two initial black holes touch, and ends when
their singularities merge, completing the formation of the final single
black hole.
An interesting
feature of these mergers is the final “kick”. Gravitational waves have
linear momentum. Depending on the exact alignments at the instant of
merger, the final black hole may have significant linear momentum that
carries it away from the orbital center. To make this more evident, the
time scale in each video runs 100 times faster after ringdown.
Some videos
“freeze” just before merger to allow viewers to better see the final
spin orientations.
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