Millennium Run: Difference between revisions
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==Size of the simulation== |
==Size of the simulation== |
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For the first scientific results, published on June 2, 2005, the Millennium Simulation traced 2160{{Sup|3}}, or just over 10 billion, "particles." These are not particles in the [[particle physics]] sense - each "particle" represents approximately a billion [[solar mass]]es of dark matter.<ref name="arxiv_supplement">{{cite web | author = Springel, Volker et al. | title = Simulating the joint evolution of quasars, galaxies and their large-scale distribution | url = http://arxiv.org/abs/astro-ph/0504097 | accessdate = 2009-05-28 | year = 2005}}</ref> The region of space simulated was a [[cube (geometry)|cube]] with about 2 billion [[light year]]s as its length.<ref name="short_nature_paper"/> This volume was populated by about 20 million "galaxies". A [[super computer]] located in [[Garching]], Germany executed the simulation, which used a version of the [[GADGET]] code, for more than a month. The output of the simulation needed about 25 [[Terabytes]] for storage.<ref>{{cite web | title = Millennium Simulation - The Largest Ever Model of the Universe | url = http://www.sciencedaily.com/releases/2005/06/050604061156.htm | accessdate = 2009-05-28}}</ref> |
For the first scientific results, published on June 2, 2005, the Millennium Simulation traced 2160{{Sup|3}}, or just over 10 billion, "particles." These are not particles in the [[particle physics]] sense - each "particle" represents approximately a billion [[solar mass]]es of dark matter.<ref name="arxiv_supplement">{{cite web | author = Springel, Volker et al. | title = Simulating the joint evolution of quasars, galaxies and their large-scale distribution | url = http://arxiv.org/abs/astro-ph/0504097 | accessdate = 2009-05-28 | year = 2005}}</ref> The region of space simulated was a [[cube (geometry)|cube]] with about 2 billion [[light year]]s as its length.<ref name="short_nature_paper"/> This volume was populated by about 20 million "galaxies". A [[super computer]] located in [[Garching]], Germany executed the simulation, which used a version of the [[GADGET]] code, for more than a month. The output of the simulation needed about 25 [[Terabytes]] for storage.<ref>{{cite web | title = Millennium Simulation - The Largest Ever Model of the Universe | url = http://www.sciencedaily.com/releases/2005/06/050604061156.htm | accessdate = 2009-05-28}}</ref> |
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In 2009, the same group ran the 'Millennium II' simulation on a smaller cube (about 400 million light years on a side), with the same number of particles but with each particle representing 6.9 million solar masses. This is a rather harder numerical task since splitting the computational domain between processors becomes harder when dense clumps of matter are present. MS-II used 1.4 million CPU hours over 2048 cores (IE about a month) on the Power-6 computer at Garching; a simulation was also run with the same initial conditions and fewer particles to check that features in the higher-resolution run were also seen at lower resolution. |
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==First results== |
==First results== |
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*[http://www.mpa-garching.mpg.de/millennium/ Millennium Simulation Data Page] |
*[http://www.mpa-garching.mpg.de/millennium/ Millennium Simulation Data Page] |
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*[http://arxiv.org/abs/astro-ph/0504097 Preprint at arxiv] |
*[http://arxiv.org/abs/astro-ph/0504097 Preprint at arxiv] |
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*[http://arxiv.org/abs/0903.3041 Preprint for Millennium II at arxiv] |
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*[http://www.mpg.de/english/illustrationsDocumentation/documentation/pressReleases/2005/pressRelease20050517/ Press release of the June 2 results (MPG)] |
*[http://www.mpg.de/english/illustrationsDocumentation/documentation/pressReleases/2005/pressRelease20050517/ Press release of the June 2 results (MPG)] |
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*[http://www.virgo.dur.ac.uk/ VIRGO home page] |
*[http://www.virgo.dur.ac.uk/ VIRGO home page] |
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Revision as of 17:03, 15 January 2010
The Millennium Run, also called the Millennium Simulation because of its size,[1][2] is the name of a computer N-body simulation which was run in order to investigate how matter in the Universe evolved over time. It is used by scientists working in physical cosmology to compare observations with theoretical predictions.
Overview
A basic scientific tool to test theories in cosmology is to evaluate their consequences for the observable parts of the universe. One piece of observational evidence is the distribution of matter, including galaxies and intergalactic gas, which are observed today. Light emitted from more distant matter must travel longer in order to reach Earth, meaning looking at distant objects is like looking further back in time. This means the evolution in time of the matter distribution in the Universe can be observed.
The Millennium Simulation was run in 2005 by the Virgo Consortium, an international group of astrophysicists from Germany, the United Kingdom, Canada, Japan and the United States. It starts at the epoch when the cosmic background radiation was emitted, about 379,000 years after the universe began. The cosmic background radiation has been studied by satellite experiments, and the observed inhomogeneities in the cosmic background serve as the starting point for the corresponding matter distribution. Using the physical laws expected to hold in the currently known cosmologies, the initial distribution of matter is allowed to evolve, and the formation of galaxies and black holes in the simulation are recorded.
Size of the simulation
For the first scientific results, published on June 2, 2005, the Millennium Simulation traced 21603, or just over 10 billion, "particles." These are not particles in the particle physics sense - each "particle" represents approximately a billion solar masses of dark matter.[3] The region of space simulated was a cube with about 2 billion light years as its length.[1] This volume was populated by about 20 million "galaxies". A super computer located in Garching, Germany executed the simulation, which used a version of the GADGET code, for more than a month. The output of the simulation needed about 25 Terabytes for storage.[4]
In 2009, the same group ran the 'Millennium II' simulation on a smaller cube (about 400 million light years on a side), with the same number of particles but with each particle representing 6.9 million solar masses. This is a rather harder numerical task since splitting the computational domain between processors becomes harder when dense clumps of matter are present. MS-II used 1.4 million CPU hours over 2048 cores (IE about a month) on the Power-6 computer at Garching; a simulation was also run with the same initial conditions and fewer particles to check that features in the higher-resolution run were also seen at lower resolution.
First results
The Sloan Digital Sky Survey had challenged the current understanding of cosmology by finding black hole candidates in very bright quasars at large distances. This meant that they were created much earlier than initially expected. In successfully managing to produce quasars at early times, the Millennium Simulation demonstrated that these objects do not contradict our models of the evolution of the Universe.
References
- ^ a b Springel, Volker; et al. (2005). "Simulations of the formation, evolution, and clustering of galaxies and quasars". Nature. 435: 629–636. doi:10.1038/nature03597.
{{cite journal}}: Explicit use of et al. in:|author=(help); Unknown parameter|month=ignored (help) - ^ "MPA :: Current Research Highlight :: August 2004". Retrieved 2009-05-28.
- ^ Springel, Volker; et al. (2005). "Simulating the joint evolution of quasars, galaxies and their large-scale distribution". Retrieved 2009-05-28.
{{cite web}}: Explicit use of et al. in:|author=(help) - ^ "Millennium Simulation - The Largest Ever Model of the Universe". Retrieved 2009-05-28.