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The following movies visualize the density of 3 colliding galaxies. The masses of the black holes have been ignored. This is just a proof of concept.

The system consists of 14000 particles and 3 black holes.

The following movie was created using the following algorithm for each frame:

The left part shows the gas particles only. It looks like a collapse does happen at the beginning. Also, as you can see the density increases in the center of the galaxy over time. Also it looks like, that some gas particle do not move at all.

The right part shows the cloud particle only. The particles are evenly distributed. Maybe slightly higher in the center. Then from the center a ring is forming. The ring gets bigger over time, and the density decreases in the center (gas_cloud_bs_1_6pbb.mov)

milky way: (.mov)

4_2: (.mov) 4_2_new: (.mov)

The following movies show star Cluster disruption near the centre of our galaxy; they are exposed to strong tidal forces, which first elongate and then disperse the cluster. The nature of the tidal forces differs in the two cases considered in the simulations: case 1 takes into account the gravity of the central black hole only, case 2 includes the tidal forces due to the mass of a spherical dense star cluster surrounding the black hole (since this component is assumed to be statically linked to the black hole it is not visualised) case 1 develops spiral patterns, consisting of stars originally bound to the infalling disrupted star cluster, while case 2 exhibits ring-like patterns.

Collaborators: Rainer Spurzem, David Merritt, Hans-Peter Bischof, Stefan Harfst, and Ortwin Gerhard.

The following movie shows star Cluster disruption near the centre of our galaxy; the supermassive black hole therein (large/red point) exerts strong tidal forces, which first elongate and then disperse the cluster into ring-like patterns, consisting of the stars orginally bound in the cluster.

Collaborators: Rainer Spurzem, David Merritt, Hans-Peter Bischof, Stefan Harfst, and Ortwin Gerhard.

The following visualizations show the density center and density radius. The nearest neighbor algorithms are used to determine the density center and density radius. More information can be found in: Casertano S., Hut P., 1985, ApJ, 298, 80 Casertano S., Hut P., 1985, ApJ, 298, 80

An artificial stellar system was created to test the implemented algorithm. The galaxy has a radius of 2 and the density decrease from the center to the border in a linear way. The density in the center is 1000 /(0.01)^3 unit and 0 at the border. The center moves over time from -1/-1/-1 to 1/1/1. The movie can be seen here: (.mov)

The same algorithm was used to create a visualization of a core collapse. The visualization shows the beginning of the collapse. The red sphere represents the highest density around a particle. The density calculation was based on the 6 nearest neighbors. The galaxy has 8192 particles, including one black hole. The density of the volume determines the color of the particle. The movie can be seen here: (.mov). The data was provided by David Merritt and Andras Szell. A snapshot was take each second. This is the reason for the rapid movement of the the red sphere.

The following visualization is based on the same data as the above visualization. The particles are not show in this case. The density calculation was based on the 6 nearest neighbors. The radius of the red sphere is the density radius. The red sphere represents the highest density around a particle. The movie can be seen here: (.mov). The data was provided by David Merritt and Andras Szell. A snapshot was take each second. This is the reason for the rapid movement of the the red sphere.

The following visualization is based on the same data as the above visualization. The particles are not show in this case. The density calculation was based on the 100 nearest neighbors. The radius of the red sphere is the density radius. The red sphere represents the highest density around a particle. . The movie can be seen here: (.mov). The data was provided by David Merritt and Andras Szell. A snapshot was take each second. This is the reason for the rapid movement of the the red sphere.

This is a best of movies. Hans-Peter Bischof (hpb@cs.rit.edu) selected the movies.

These movies show the past n positions of the black holes. In other words you will see a trail of the black holes.

The following movies shows Brownian motion of a single black hole at the center of a galaxy from 0.1/0.1/1.3. The movie was made with 20 frames/second. The data was provided by David Merritt and Andras Szell. dehnen movie

The following movies shows a variation of the plummer model. The data was provided by Piet Hut. plummer movie

The eight body movie consist of three parts. The first parts shows the increasing speed of the black holes. Delta t = 0.01. The camera is at position 4/1.6/0.6. Then deltaT is set to 0.001, the camera moves to 0.8/0.9/0.6, and the black hole size is reduced to 0.005. Finally the camera moves to 2.3/1.7/0.6. The data was provided by Piet Hut. 8 body movie

The data was provided by Piet Hut. All movies show a plummer simulation.

delta T for the visualization was 0.01
No linear interpolation was used
The following movie .mov was created from data, with delta t = 0.01. No linear interpolation was used, in other words, 20002 / 8 time stamps have been used per particle. No linear interpolation was used, the particles appear in the provide data often enough, therefore a linear interpolation was not necessary. The movie was made with 50 frames/sec.

delta T for the visualization was 0.01
No linear interpolation was used
The following movie .mov used output that has been rinted asynchronously: for every particle, output is provided for only one out of ten steps (with the exception that some extra outputs may appear at the end of what we call an era, here 0.1 time units long; in any case, there is at least one output per ten time steps). Text is from Piet. No interpolation was used, in other words, the black holes will jump. The movie was made with 50 frames/sec.

delta T for the visualization was 0.01
Linear Interpolation was used
The following movie .mov used output that has been rinted asynchronously: for every particle, output is provided for only one out of ten steps (with the exception that some extra outputs may appear at the end of what we call an era, here 0.1 time units long; in any case, there is at least one output per ten time steps). Text is from Piet. Linear Interpolation was used. This means 9 out of 10 positions have been calculated. The movie was made with 50 frames/sec.

delta T for the visualization was 0.001
Linear Interpolation was used
The following movie .mov used 0.001 as delta t for the visualization. Linear Interpolation was used. This means 99 out of 100 positions have been calculated. The movie is therefore 10 time slower. The visualization was stopped after 3 time units. The movie was made with 50 frames/sec.

The following movies will show Brownian motion of a single black hole at the center of a galaxy from 2.0/0.19/0.23. The first two movie are made with 60 frames/second and contains ~ 1100 images. The last movie is made with 60 frames/second and contains ~ 2220 images.

The initial conditions are:

The following movies visualize the same situation from the same view point.

The data was provided by David Merritt and Andras Szell.

This movie visualizes a plummer model from as seen from 4.0/1.6/0.6. It shows a 16-body system, with quite a bit of interactions between binaries that are formed by chance, interact with each other, and often are broken up again in the process, though some binaries will grow tighter and survive. The data was provided by Piet Hut.
This movie visualizes a plummer model from as seen from 4.0/1.6/0.6.

This movie visualizes a plummer model from as seen from 4.0/20/-20 The data was provided by Piet Hut. The following makefile snippet created the movie: 

piet:   
        $(JAVA) $(JFLAGS) spiegel.Spiegel       \
        --feeder-port=1000                      \
        --debug=false                           \
        --batch=true                            \
        --dirName=Gif_Piet                      \
        --inputFileName=../Data/plummer.sim   \
        --deltaT=0.005                          \
        --flyPath="Piet"                        \
        --createMovie=true                      \
        --peek=true                             \
        --blackHoles=5
The camera looks at the center and does not move.

The Plummer system movie

This movie visualizes an eight body system. The original code was take from Piet Hut's and Jun Makinos Kali Code for Dense Stellar Systems. A few modifications of the print statements have been necessary. The following command creates the data (61881234bytes, rknbody8b.sim) which was used for the visualization. 
ruby rknbody8b_driver.rb < cube1.in | sed 's/\.0//' > rknbody8b.sim
dt = 0.0001
dt_dia = 1
dt_out = 10
dt_end = 2.5
init_out = false
x_flag = true
method = rk4
The following makefile snippet created the movie: 
piet:   
        $(JAVA) $(JFLAGS) spiegel.Spiegel       \
        --feeder-port=1000                      \
        --debug=false                           \
        --batch=true                            \
        --dirName=Gif_Piet                      \
        --inputFileName=../Data/rknbody8b.sim   \
        --deltaT=0.005                          \
        --flyPath="Piet"                        \
        --createMovie=true                      \
        --peek=true                             \
        --blackHoles=8
The camera looks at the center and does not move.

The Eight body system movie: .mov .avi

This movie visualize three merging galaxies. The camera looks at the center of the largest galaxies, and is positioned relativly close to the black hole in the center.

What will you see? 3 black holes advancing over time. Please watch the black hole on the right at the beginning of the visualization.

This movie visualize three merging galaxies. The camera looks at the center of the largest galaxies, and is positioned relativly close to the black hole in the center.

What will you see? 3 black holes and 14000 particles advancing over time. Please watch the black hole on the right at the beginning of the visualization.

This example shows how the language Spiegel can be used. The basic idea is, that a pre-processor generates the statements which will be executed by the Spiegel system.

First, the pre-processor generates Spiegel statements which are used as input in order to create the final movie. The system is used to generate the Spiegel statements. The camera looks at the ball.

Second, the generate statements are stored in a file, and fed to the Spiegel system. The file can be seen here.

Third, the final movie is create, and can be seen here.

This movie contains 5000 particles, three galaxies (three back holes).

What will you see? The particles advance over time and leave a trace behind. The original simulation was done with 14000 particles. I extracted 5000 of them.

This movie contains 14000 particles, three galaxies (three back holes).

What will you see? 14000 particles advance over time and leave a trace behind. This is a very short movie, just about 2 seconds.

This movie contains 14000 particles, three galaxies (three back holes).

What will you see? First the camera moves around and gives you an overview. Then the particles advance over time. This is a very dramatic movie.

This movie contains 14000 particles, two galaxies (two back holes).

What will you see? First the camera moves around and gives you an overview. Then the particles advance over time. The camera will move closer to the black holes when if get's interesting.

The GRAPEcluster Project RIT Astrophysics Group/Department of Computer Science Rochester Institute of Technology
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