Cosmological Structure Formation in the Supercomputer
Numerical simulation of the formation of a filament containing
hundreds of galaxies
During the early inflationary phase of the
evolution of the Universe
quantum fluctuations became classical perturbations
in the density
field. Within numerical simulation we follow the
nonlinear growth of
these density fluctuations using the ART code
on up to 1024 CPUs. The
requirements for modern cosmological simulations
are extreme: a very
large dynamical range for force resolution and many millions of
particles are needed. These requirements are just a reflection of the
vast range of masses and spatial scales in real astronomical
objects. For example, from dwarf galaxies to galaxy clusters the mass
spans about 7 orders of magnitude. The range of
scales is also
enormous: from the inner structure of galaxies (sub-kiloparsec scales)
to cosmological distances of many megaparsecs (1 pc = 3.26 light
years). For the simulation shown in the figure we used more than 150
million particles within the high resolution region. The mass
resolution is 5*106 M_sun and hence a Milky Way galaxy is represented
by 200 000 particles. The force resolution is 300 pc. The total CPU
time used for this simulation was about 300,000 CPU hours. The
figure shows a region of 35 Mpc size. It is a small part (3 %) of a
larger simulation with a total volume of
(115 Mpc)3. One can clearly
see the filamentary structure. The first blow-up shows a region of 10
Mpc and the second one of 2 Mpc. The object in the second blow-up has
a mass comparable to our Milky Way. Satellites can be clearly
seen. With such simulations we study the formation of galaxies
in different environments.
(Stefan Gottlöber, Arman Khalatyan (Astrophysikalisches Institut Potsdam),
Anatoly Klypin (New Mexico State University))
Ludger Palm