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  • Universe in a box: formation of large-scale structure
    bursts of star formation and resulting in the different types of structures observed today The sequence of events is thought to be seeded by quantum fluctuations in the very early Universe These tiniest fluctuations were stretched by many orders of magnitude during a brief period of extremely rapid exponential expansion of the Universe called inflation The growth of structures is thought to be governed by mysterious dark matter which constitutes

    Original URL path: http://cosmicweb.uchicago.edu/ (2012-11-10)
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  • Universe in a box: formation of large-scale structure
    this here In order to make it simpler to visualize the formation of structures the expansion can be taken out so that the simulation box appears static In professional lingo the system of coordinates that expands or co moves with the Universe is called the comoving coordinate system As the Universe expands galaxies become more and more distant from each other For an observer such as ourselves it appears that all other galaxies fly away from us The further the galaxy the faster it appears to recede This recession affects the light emitted by the distant galaxies stretching the wavelengths of emitted photons due to the Doppler redshift effect The distance between galaxies is proportionalto the measure of this effect 1 z where z is what astronomers call redshift The redshift can be measured for each object if its spectrum is measured In addition it takes a very long time up to several billion years for the light from the most distant galaxies and quasars to reach us Not only the light we receive from these objects is redshifted but we also see these objects as they were during the early stages in the evolution of the Universe In this sense the redshift z provides a universal clock and can be used as a measure of time Observations of distant galaxies is much like a time travel into the past In the subsequent pages you can find a series of pictures and animations illustrating formation of structures in the Cold Dark Matter Universes The animations were created using outputs of the high resolution simulations performed at the National Center for Supercomputer Simulations NCSA The simulations followed evolution of perturbations assuming a flat universe in which 30 of density is due to matter and 70 due to vacuum energy or dark

    Original URL path: http://cosmicweb.uchicago.edu/sims.html (2012-11-10)
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  • Universe in a box: formation of large-scale structure
    panel At the initial epoch z 30 when the age of the Universe was less than 1 of its current age distribution of matter appears to be uniform This is because the seed fluctuations are still fairly small As time goes on the fluctuations grow resulting in a wealth of structures from the smallest bright clumps which have sizes and masses similar to those of galaxies to the large filaments Notice the filament spanning the entire box from left to right and how it becomes more and more pronounced with time Also note that it does not change much between z 0 5 and z 0 i e the last two panels This is because the expansion of the universe is in the stage of acceleration as the dark energy becomes dominant at z You can download the movie as an MPEG movie full size 10Mb half size 1 3Mb The same simulation but with a rotating box 3D geometry of the filaments can be appreciated better an animated gif half size 5Mb quarter size 1Mb MPEG movie full size 9Mb half size 1Mb The same as above but in a single picture The frames show the evolution of structures

    Original URL path: http://cosmicweb.uchicago.edu/filaments.html (2012-11-10)
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  • Universe in a box: formation of a galaxy group
    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 You can download the movie as an MPEG movie full size 11Mb half size 2 8Mb an animated GIF half size 6Mb

    Original URL path: http://cosmicweb.uchicago.edu/group.html (2012-11-10)
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  • Universe in a box: formation of a galaxy
    filaments of matter intersects These filaments deliver a fresh supply of gas and dark matter to the galaxy The acretting gas fuels very active star formation while accreted dark matter and smaller galaxies lead to the rapid growth of the galaxy s mass In the top panels showing the smallest regions you can see a young spiral disk The disk is forming stars very actively with regions of star formation concentrated towards the densest regions near the plane of the disk the brightest blue and so the distribution of stars is also disk like Unlike gas however the stars can be heated by frequent collisions and mergers with other galaxies common at these early epochs Therefore the stellar disk is somewhat thicker than the gas disk The distribution of stars in the disk is shown in the two panels face on and edge on view below The stellar particles were color coded according to their age so that white colored stars are the youngest and red are the oldest You can see that the youngest stars concentrate towards the plane of the disk and the central regions while the old stars have a more extended distribution and form what astronomers

    Original URL path: http://cosmicweb.uchicago.edu/gal.html (2012-11-10)
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  • Universe in a box: screensavers
    system32 and select the screen saver through the Display Settings MacOS 9 version 5 2 Mb of the screensaver Point and click on the link the screensaver should be automatically downloaded and unpacked Screensaver installer icon should appear on the Desktop If you click on the icon the screesaver will be installed on your Macintosh machine MacOS X version 5 5 Mb of the screensaver Point and click on the

    Original URL path: http://cosmicweb.uchicago.edu/screen.html (2012-11-10)
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  • Universe in a box: formation of large-scale structure
    the PBS program of the same name Great visual introduction to the concepts discussed here Walls within Voids introduction to the observational efforts to map the large scale structure from NCSA Wayne Hu s Introduction to the Cosmic Microwave Background and origin of structures Ned Wright s Cosmology Tutorial The Adventure of Experimental Cosmology public Compton lectures series by Clem Pryke Observational Tests of Big Bang Cosmology public Compton lectures

    Original URL path: http://cosmicweb.uchicago.edu/links.html (2012-11-10)
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