Evolution of a Local Group like system in the CDM universe
with dark energy
see also this web page
The movie shows a zoom-on on one particular region of the large box
shown in the previous movie. You see formation of a group of galaxies quite
similar to our Local Group in which our galaxy, the Milky Way, is
approaching our biggest neighbor the Andromeda Galaxy. The region
shown here is 1/10 of the box shown in the filament formation page and
is equal to 4.3 megaparsec or 14 million light years. Our "camera" is
tracking the progenitor of the group so that it is always new the
center of the field of view. The formation of an object such as our
Local Group proceeds hierarchically in the Cold Dark Matter
models. Small-mass objects form first at z>5, they quickly grow in
size and violently merge with each other, creating increasingly larger
and larger system. This galactic "cannibalism" persists even to the
present day epoch (z=0). Indeed, the two main objects that you can see
approaching at z~0, will also merge in about one billion years into
the future. Note that many of the "cannibalized" systems do not loose
their identity and become satellites orbiting in the gravitational
pull of larger systems. The groups like the one modeled in these
simulations are very common in the Universe. In fact, up to half of
all galaxies are thought to be part of groups of different sizes.
Questions and comments: Andrey Kravtsov (andrey@oddjob.uchicago.edu)
You can use this material if you include the proper credit:
simulations were performed at the National
Center for Supercomputer Applications
by
Andrey Kravtsov
(Kavli Institute for Cosmological Physics, The University of Chicago)
and Anatoly Klypin
(New Mexico State University).
Visualizations
by Andrey Kravtsov.