Simon Portegies Zwart (Univ. Amsterdam with 2 GRAPE-6 boards)

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Simulation of star cluster (6144 stars) done with GRAPE-4; watch for ejection of high-velocity star on left side about 1/3 of the way through the animation

Star cluster Palomar-5 (from the SDSS)

Simulation of star cluster(6500 stars) orbiting the galactic center for 0.75 Myr. Initial density profile is a King model. Cluster starts at 4pc from galactic center but spirals in. 1 orbit = 105 yrs. Notice the star colors in the tidal tails; these researchers include stellar evolution with dynamics!

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Accretion of ~200 satellite galaxies by the MW; simulation by James Bullock and Kathryn Johnson; context: Cold Dark Matter is hierarchical when it comes to structure formation

Real Host and Satellite Galaxies from the SDSS!

B-band surface brightness expected for Milky Way- type galaxy after accretion of satellites;

Projection is 300 kpc X 300 kpc

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Galaxy collisions are important for establishment of morphology. Disks are extremely FRAGILE.

simulation by Volker Springel at MPIA

Note: this is a gravity + gas simulation; the spirals are in the gas not the dark matter

Cold Dark Matter (WIMPs)

Warm Dark Matter (mostly CDM but with some neutrinos as well)

Hot Dark Matter (neutrinos)

Simulations by Ben Moore (Univ. of Zurich)

One of these is the actual Coma cluster; one is a dark matter simulation of a cluster by Ben Moore

CDM generically gives “filamentary” structure in the universe (another of Ben Moore’s simulations)

Galaxies are observed to be “clustered” in space (not random)

Which one is the 2dFGRS? Which are taken from CDM simulations?

CDM generically predicts mildly-flattened halos (<e> ~ 0.3) with a lot of dark matter substructure

Spherically-averaged density profile is NOT isothermal (“Navarro, Frenk & White”)

Milky Way sized halo from one of Ben Moore’s simulations

Changing the cosmological parameters (but not the type of dark matter) radically changes the history of structure formation

“State of the Art” in 1996 (Volker Springel et al.)

2563 particles, mp=2.3x109 Msun to 6.9x109 Msun, 240 x 240 x 240 Mpc box

“Adaptive” P3M code

Millennium Run Simulation(Volker Springel et al. 2005)

• Largest CDM simulation ever run (> 10 billion particles)

• mp = 8.6 x 108 Msun

• 500 Mpc x 500 Mpc x 500 Mpc box• TreePM• Force resolution of 5 kpc• More than 20 million galaxies• Much of the data are publicly-available (big part of Ingo’s thesis

work)

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Zoom in to a cluster at z=0

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Growth of structure from z=20 to z=0 in “comoving” coordinates