Midterm and Final Team Projects

Physics 141/241

Winter 2013

All four teams work on the Midterm projects within the framework of the Toomre&Toomre model of the restricted three-body problem. The final projects are the best full simulations of the teams using the bulge-disk-halo Dubinski model for their galaxy encounter projects.

Midterm projects will be presented on March 13.

Final projects will be presented on March 21 between 6:00 pm - 9:00 pm.

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Mice (non-cuda):
Eliashiv, Jonathan <[email protected]>
Hathrell, Holly <[email protected]>
Grini, Sigbjørn<[email protected]>

Mice (cuda):
Zhang, Boyan <[email protected]>
Egorov, Dmitry <[email protected]>
Aatish, Kumar <[email protected]>

The Mice Project (NGC 4676)

Mice Team

For convenience, Toomre&Toomre chose the time unit to be , the pericenter distance $R_{\min }=25kpc$ and the heavier mass in each encounter, $10^{11}M_{solar}$ , chosen as the mass unit. The collision orbits (elliptic, or parabolic) are identified by choosing (1) $R_{\min }=r_{p}$ and (2) the initial separation $R_{init}$ , or the equivalent time $t_{init}$ , with chosen at pericenter. Initial velocities are dependent on the masses of the galaxies. Disk orientations and other input parameters are determined from the reference material of the projects as requested in the project descriptions. For the Midterm project Toomre&Toomre disk galaxy models are prepared with test particles to run the restricted 3-body integrator. In the Final project realistic Galaxies are crafted at the origin of the coordinate system using the code of Konrad Kuijken and John Dubinski to generate disk-bulge-halo galaxies. The code is discussed in the paper by Kuijken&Dubinski and the tar file of the code is packaged galactics.tar.gz.

Midterm: Mice Project

Figure 22 on page 35 in Toomre&Toomre summarizes the initial setup of their most successive Mice encounter. Reproduce their result of Fig.22 using 297 disk particles in each disk as described on page 20. They fill 11 concentric rings of radii . Increase the filling of the rings by increments of three test particles and starting with particles on the innermost ring. The outermost ring has particles. Run your restricted 3-body code where the test particles are tracking the two elliptic orbits of the core galaxies. The test particles are interacting with the cores only. Work in the center-of-mass coordinate system where the relative coordinate vector $\overrightarrow{r}$ traces the elliptic Kepler orbit. For the elliptic orbits, use the appropriate parametrization as it was outlined in Lecture 5:

The origin of the CM coordinate system cn be chosen to coincide with the Sun location of the figure. Two equal disks of radius $0.7R_{\min }$ experience an elliptic encounter with , having begun flat and circular at the time of the last apocenter. As viewed from either disk, the adopted node to peri angles with inclinations . The angles are discussed in Fig. 6a,b (see also Galaxy Rotations note and collision orbit note). The resulting composite object is shown at in Fig. 22.

(1) Compare Toomre&Toomre to your simulation.

(2) Animate and make an Mpeg movie.

(3) Give a simple explanation of the tidal tails and explain whether the tidal tails are in the plane of the rotating disks, or the collision plane, or neither.

(4) Write a project report and prepare a 20 minutes presentation.

Final: Project Mice

Barnes in his paper argued that a realistic full simulation of the encounter using realistic bulge-disk-halo galaxy model calls for parabolic encounter. He gave arguments that the bulge-disk-halo galaxy structure requires to replace the elliptic encounter of Toomre&Toomre with parabolic encounter. For the initial condition, consider to separate galaxies on parabolic collision course. Galaxy A and galaxy B do not overlap initially, and the center of masses of the individual galaxies would continue on a parabolic orbit, if the interactions of the stars would not change the picture when the galaxies begin to overlap.

First, we would like to set up the appropriate initial condition for the collision as depicted in the figure above. Notes on the setup are given in collision orbit note. Notes on the disk angles are given in Galaxy Rotations note. Barnes chose in the paper the length unit to be , the velocity unit as , and the mass unit as . One time unit then works out to be . Barnes chose for the galaxy components: Parabolic orbit was chosen with $r_{p}=0.25,$ $r_{disk}=1/12,$ $a_{b}=0.04168,$ $z_{disk}=0.005,$ $a_{halo}=0.1$ . The viewing time of the encounter is after pericenter. The disk angles are .

(1) Use the Galactics package to fabricate the initial galaxies. Choose your resolution for the project.

(2) Run Gyrfalcon to reproduce the results of Barnes in the article.

(3) Animate and make Mpeg movies of the project.

(4) Give again simple explanation of the consistency of tidal tails with Toomre&Toomre and explain again whether the tidal tails are in the plane of the rotating disks, or the collision plane, or neither.

(5) Write a project report and prepare a 20 minutes presentation.

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Antennae A (non-cuda):
Myers, Jared <[email protected]>
Webb, Catrina <[email protected]>
Yari, Cheyenne <[email protected]>

Antennae A (cuda):
Le, Justin <[email protected]>
Lee, Christoph <[email protected]>
Berkowitz, John <[email protected]>

Antennae B (non-cuda):
Hall, William <[email protected]>
Granerød, Cecilie <[email protected]>

Antennae B (cuda):
Eldridge, Michael <[email protected]>
Rozdeba, Paul <[email protected]>
Briggs, Andrew <[email protected]>

The Antennae Project (NGC 4038/9)

Antennae Team A and Antennae Team B

For convenience, Toomre&Toomre chose the time unit to be , the pericenter distance $R_{\min }=25kpc$ and the heavier mass in each encounter, $10^{11}M_{solar},$ chosen as the unit mass. The collision orbits (elliptic, or parabolic) are identified by choosing (1) $R_{\min }=r_{p}$ and (2) the initial separation $R_{init}$ , or the equivalent time $t_{init}$ , with chosen at pericenter. Initial velocities are dependent on the masses of the galaxies. Disk orientations and other input parameters are determined from the reference material of the projects as requested in the project descriptions. For the Midterm project Toomre&Toomre disk galaxy models are prepared with test particles to run the restricted 3-body integrator. In the Final project realistic Galaxies are crafted at the origin of the coordinate system using the code of Konrad Kuijken and John Dubinski to generate disk-bulge-halo galaxies. The code is discussed in the paper by Kuijken&Dubinski and the tar file of the code is packaged Galactics.tar.gz.

Midterm: Antennae Project

Figure 23 on page 37 in Toomre&Toomre summarizes the initial setup of their symmetric Antennae encounter. Reproduce their result of Fig.23 using 345 disk particles in each disk as described on page 20. They fill 12 concentric rings of radii . Increase the filling of the rings by increments of three test particles added to the next ring and starting with particles on the innermost ring. The outermost ring has particles. Run your restricted 3-body code where the test particles are tracking the two elliptic orbits of the core galaxies with . The test particles are interacting with the cores only and the interaction is softened by at the closest range to mimic the distributed mass of the real object. Work in the center-of-mass coordinate system where the relative coordinate vector $\overrightarrow{r}$ traces the elliptic Kepler orbit. For the elliptic orbits, use the appropriate parametrization as it was outlined in Lecture 5:

The origin of the CM coordinate system can be chosen to coincide with the Sun location of the figure. Two equal disks of radius $0.75R_{\min }$ experience an elliptic encounter, having begun flat and circular at the time of the last apocenter. As viewed from either disk, the adopted node to peri angles with inclinations . The angles are discussed in Fig. 6a,b (see also Galaxy Rotations note and collision orbit note). The viewing time of the resulting composite object is in Fig. 23.

(1) Compare Toomre&Toomre to your simulation.

(2) Animate and make an Mpeg movie.

(3) Give a simple explanation of the tidal tails and explain whether the tidal tails are in the plane of the rotating disks, or the collision plane, or neither.

(4) Write a project report and prepare a 20 minutes presentation.

Final: Antennae Project

Barnes in his paper on the Antennae designed a realistic full simulation of the encounter using realistic bulge-disk-halo galaxy model with elliptic encounter. For the initial condition, consider to separate galaxies on elliptic collision course with . Galaxy A and galaxy B do not overlap initially, and the center of masses of the individual galaxies would continue on an elliptic orbit, if the interactions of the stars would not change the picture when the galaxies begin to overlap.

First, we would like to set up the appropriate initial condition for the collision as depicted in the figure above, but the parbolic orbits replaced by elliptic ones. Notes on the setup for parbolic orbits are given in collision orbit note and have to be replaced by the properties of elliptic orbits. Notes on the disk angles are given in Galaxy Rotations note. Barnes chose in the paper the length unit to be , and the mass unit as . One time unit is . Barnes chose for the galaxy components: with a total mass Elliptic orbits were chosen and started with $r_{p}=0.5,$ $r_{disk}=1/12,$ node to peri angles with inclinations and time to epicenter to produce a slow and symmetrically prograde encounter with the two disks inclined so as to sling tidal tails high above the orbital plane where they will eventually be seen in projection as crossing each other. The viewing time of the encounter is close to the nex apocenter.

(1) Use the Galactics package to fabricate the initial galaxies. Choose your resolution for the project.

(2) Run Gyrfalcon to reproduce the results of Barnes in the article.

(3) Animate and make Mpeg movies of the project.

(5) Write a project report and prepare a 20 minutes presentation.

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Cartwheel (non-cuda):
Spiro, Kevin <[email protected]>
Wampler, James <[email protected]>
Leon, David <[email protected]>

Cartwheel (cuda):
Sheldon, Forrest <[email protected]>
Walsh, Daniel <[email protected]>

Cartwheel Project

Cartwheel Team A and Cartwheel Team B

Midterm: Cartwheel

In the spirit of the Toomre&Toomre modeling of the Mice, Antennae, and Milky Way mergers, study the paper by Lynds&Toomre to set up and reproduce their model.

(1) Obtain Lynds&Toomre models mimicking the mergers of Figs. 5 and 6 in the paper.

(2) Animate and make Mpeg movies of your mergers.

(3) Give a simple explanation of the Cartwheel.

(4) Write a project report and prepare a 20 minutes presentation.

Final: Cartwheel

In the spirit of realistic modeling of galaxy mergers, like the Mice, Antennae, and Milky Way mergers, study the paper by Athanassoula et al. to set up and reproduce their model of the Cartwheel using bulge-disk-halo galaxies.

(1) Use the Galactics package to fabricate the initial galaxies. Choose your resolution for the project.

(2) Run Gyrfalcon to get close to the results of Athanassoula et al. as reported in their paper. Consider also the Aarseth code, if it suits better the project, in case of demand on accuracy.

(3) Animate and make Mpeg movies of the project.

(4) Give again simple explanation of how the Cartwheel merger happened.

(5) Write a project report and prepare a 20 minutes presentation.

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