Movies

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Watch clips of black holes (Black Hole: A region of spacetime (Spacetime: A concept in physics which merges our usual notion of space with our usual notion of time.) where the warpage of both space and time (gravity) is so intense that nothing — even light — can ever escape. Objects may fall in to the Black Hole, but once they pass the Event Horizon (Event Horizon: A surface — like the one surrounding a Black Hole — enclosing a region of space from which nothing (even light) can ever escape.), they can never escape again. Most Black Holes believed to exist are thought to be formed in the collapse of very large stars, or the collision of stars or other Black Holes. )})|blackholes}) colliding

Highly-precessing binary black hole (Black Hole: A region of spacetime where the warpage of both space and time (gravity) is so intense that nothing — even light — can ever escape. Objects may fall in to the Black Hole, but once they pass the Event Horizon, they can never escape again. Most Black Holes believed to exist are thought to be formed in the collapse of very large stars, or the collision of stars or other Black Holes. ) run

Binary black hole system with spin (Spin: An intrinsic property of particles. (That is, a property which does not change. Mass and electric charge are examples of intrinsic properties.) Spin is related to the usual notion of spin, though it is a little more difficult to understand. Spin comes in units of 1/2, so that a particle may have a spin of 0, 1/2, 1, 3/2, and so on. A particle's spin determines whether it is a Fermion or a Boson.) 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.

 

Vortex-Tendex Visualization

Head-on Collision of Equal-Mass Black Holes with Transvere Spins

The spins of the black holes are transverse to the infall direction, anti-aligned and of magnitude 0.5. This simulation is descrbed in a publication Phys. Rev. D, also available at gr-qc/0907.0869.

 

Inspiral (Inspiral: The gradually-shrinking orbit of a binary system. As the pair of stars in the binary orbit each other, they give off energy in the form of gravitational waves. This lost energy draws them closer in their orbit — eventually resulting in a Merger (Merger: The portion of the Inspiral of a binary system in which the individual objects are highly distorted, and their orbit is changing rapidly. This portion is not well-understood, and must be simulated using Numerical Relativity (Numerical Relativity: The branch of Relativity research which deals with simulating the development of Spacetime, using computers. This is believed to be the only possible way to understand things like the merger of two Black Holes.).).) of Equal-Mass Black Holes with Spin Anti-Aligned to the Orbital Angular Momentum and of Magnitude 0.95

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 at arXiv:1010.2777.

 

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 (Phase: For a wave, the position of any particular feature of the wave. For matter, a distinct form of a substance, such as solid, liquid, or vapor. ) 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 at arXiv:1012.4869.

 



Demo: Binary Orbit & Collision, Head-on Collision

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.

 

Falling Spacetime

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 (Ringdown: The portion of an Inspiral, following the Merger, when the two objects have combined into one. During this brief period, the combined object will settle down by giving off gravitational waves.).

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 (Gravitational Wave: A gravitational disturbance that travels through space like a wave. This type of wave is analogous to an Electromagnetic Wave. Gravitational waves are given off by most movements of anything with mass. Usually, however, they are quite difficult to detect. Physicists are currently working hard to directly detect gravitational waves. Experiments like LIGO and LISA are designed for this purpose. ) 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 the “crinkles”.

 

Gravitational Waves From a Pair of Black Holes From Large Distance

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 (Gravitational Wave: A gravitational disturbance that travels through space like a wave. This type of wave is analogous to an Electromagnetic Wave. Gravitational waves are given off by most movements of anything with mass. Usually, however, they are quite difficult to detect. Physicists are currently working hard to directly detect gravitational waves. Experiments like LIGO and LISA are designed for this purpose. ) 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 collide.

 

Gravitational Waves From a Pair of Black Holes Orbiting Each Other

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.

 

Precessing Black Hole-Neutron (Neutron: One of the particles in an atomic nucleus. These particles have no electric charge, but they hold together the protons (positive particles in a nucleus), and account for roughly half of the particles in the nucleus. Neutrons are fermions, and are believed to form the majority of the matter in a neutron star.) Star (Neutron Star: A type of star which is very old, having cooled off and stopped nuclear fusion reactions. When gravity pulls the star down on itself, the electrons and protons are squeezed together, leaving just neutrons. The star is then supported against gravity by "neutron degeneracy pressure" (no two neutrons can be in the same place at the same time). These are produced when a star is too heavy to be a white dwarf (White Dwarf: A type of star which is very old, having cooled off and stopped nuclear fusion reactions. A white dwarf is supported by "electron degeneracy pressure" (no two electrons can be in the same place at the same time). These are produced when a star is not heavy enough to turn into a Neutron Star or a Black Hole. )})|white dwarves}), but not heavy enough to turn into a Black Hole. )}) Merger

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 (Observer: A person or piece of equipment that measures something in physics. Frequently, we speak of an observer measuring time or a distance in a particular place. )}) 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 timescales.

 

Merging Event Horizons

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.