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Highly-precessing binary black hole run
Binary black hole system with spin of 0.91 on the large hole and 0.3 on the small hole. The mass ratio is 6:1. Colors indicate the vorticity of the apparent horizon and arrows denote the spin directions. The large spin produces significant orbital precession.
Movie rendered by Robert McGehee and Alex Streicher.
Inspiral of Equal-Mass Black Holes with
Spin Anti-Aligned to the Orbital Angular Momentum and of Magnitude
The spins have magnitude 0.95, are parallel to each other, but are
anti-aligned with the orbital angular momentum. This simulation is
described in a publication in Phys. Rev. D., in press. The
paper can also be accessed
The evolution of the spin function (imaginary
part, χ, of the Penrose-Rindler complex curvature,
κ) on the apparent horizons
Note that aside from corrections that become important only
near the time of merger, the spin function χ and scalar
curvature R should agree well with -2Bnn and
-2Enn, respectively, where Bnn and
Enn are the horizon vorticity and tendicity, respectively.
"Extreme-Kick" Merger: Inspiral of Equal-Mass Black Holes with Spins Anti-parallel and Oriented in the Orbital Plane
The spins of the black holes are anti-parallel, oriented in the
orbital plane, and are of magnitude 0.5. In this configuration, the
kick of the final black hole has been observed in simulations
by Campanelli et al.
to depend on the phase of the binary at the time of merger; more
specifically, they found that the kick depended sinusoidally upon the
angle between the initial momenta of the BHs and the spins. This
simulation will be detailed a future publication in progress; it is
discussed in a paper submitted to Phys. Rev. Lett., available
The evolution of Enn, the tendexes, and Bnn, the vortexes, in the apparent horizons
The following movie is divided into two parts, each part showing a different
numerical simulation, with brief captions that describe
what is being shown.
Part 1: Binary black
holes orbit, lose energy because of gravitational radiation, and finally
collide, forming a single black hole; gravitational waveform, spacetime curvature, and orbital trajectories are shown. Part 2: Event horizon and apparent
horizons for the head-on collision of two black holes.
The upper movie shows in the upper half of the screen the orbits and
the apparent horizons of the two holes, in the coordinate system
used in the computation. The bottom half of the screen shows the
spacetime geometry in the holes' orbital plane. The depth of the
surface is proportional to the scalar curvature of space. (For the
two-dimensional orbital plane the full spatial curvature is
determined by the scalar curvature.) The colors encode the lapse
function — the slowing of the rate of flow of time. The
arrows show minus the shift — which can be thought of as the
velocity of flow of space. The beginning of the inspiral is shown,
and then the last several orbits, the merger of the two holes, and
the vibrational ringdown.
The final hole does not look pefectly spherical because the computer
code that created this movie chose spatial slices with a bit of
crinkliness in them at the end. This simulation lasts for 16
inspiral orbits, followed by merger and ringdown, and it achieves a
cumulative phase accuracy for the emitted gravitational waves of
about 0.02 radians (out of roughly 200 radians, i.e. a fractional
phase error of 1 part in 10,000).
Tehnical details of the simulation on which this movie is based can
be found in a paper
by the Caltech-Cornell group. Note that slightly different
data is used in that paper; the spatial slices are chosen without
On the right side, this movie shows the gravitational waves emitted
by a pair of black holes from large distance. The black holes
themselves are in the center of the ball, too small to be seen.
Toward the left of the ball showing gravitational waves, there is a
little grey dot. The red line on the left side shows the
gravitational wave strength which would be observed if a
gravitational wave detector would have been at that place. If you
look carefully, you'll notice that gravitational waves are emitted
in all directions, but that the waves are strongest in the "upward
direction", which is normal to the orbital plane of the holes.
This is an older movie, which stops just before the black holes
This movie shows a pair of black holes orbiting each other, giving off gravitational waves. The movie begins with a close-up view of the holes. We zoom out, to show some of the surrounding spacetime. As the holes go around, they give off waves. After an initial burst of "junk radiation" (unrealistic artifacts of the simulation), the animation speeds up – just so it doesn't take so long – and we see nice spiral-shaped waves. Gradually, the black holes begin to orbit faster and faster. As they do, the waves become more and more intense. If you watch carefully, you can see the circles on the top and sides oscillating, just as you would expect from a passing gravitational wave.
This movie shows the merger of a black hole-neutron star binary in which the
spin of the black hole is not aligned with the total angular momentum of the
system, thus causing the orbital plane to precess. The black hole is 3 times
more massive than the neutron star, and has a spin a=0.5 at an initial
inclination of 80 degrees with respect to the orbital angular momentum of
the binary. The main frame shows the evolution of the system from slightly
above the initial equatorial plane, with the color scale giving the density
of matter within the star, while the smaller panel shows the same system
viewed from an "edge-on" position (i.e.: as seen by an observer located in
the initial equatorial plane).
The binary goes through about 2 orbits, during which the separation between
the compact objects drops from 60km to 30km. Then, tidal forces disrupt the
neutron star. Most of the matter (~97%) is rapidly accreted by the black
hole, while the rest forms a long tidal tail which eventually settles into
an accretion disk. The relative precession of the star, tail and disk is
clearly visible in the edge-on view. Towards the end of the simulation, the
spin of the black hole and the angular momentum of the disk are misaligned
by about 20 degrees, which will cause the precession of the disk over longer
This movie shows the event horizons of two black holes merging into a single black hole. The holes have a 2:1 mass ratio, with spins of approximately 0.4 in random directions. The merger simulation has been published in gr-qc/0909.3557, by Bela Szilagyi, Lee Lindblom and Mark Scheel at Caltech. The event horizon tracking was performed by Michael Cohen at Caltech.