A team of researchers from the Laboratoire Univers et Théorie (LUTH, Observatoire de Paris/CNRS/Université Paris Diderot) (1) directed by Jean-Michel Alimi has just completed the first calculation of the entire observable Universe, from the Big Bang to the present day. The work entailed the simulation of 550 billion particles.

It is the first of three phases of the Dark Energy Universe Simulation (DEUS - Full Universe Run) project in which a full universe simulation (2) is being run on the new CURIE supercomputer, operated by the Grand Equipement National de Calcul Intensif (GENCI). The system is installed at the Très Grand Centre de Calcul (TGCC) at the CEA. The simulation that has already been run and those planned for the end of May 2012 will aid large projects and observational mapping of our Universe. They intent is to help better understand the nature of dark energy and its influence on the structure of the Universe, as well as the origin of the distribution of dark matter and galaxies.

After several years of development, six researchers (3) from the cosmology research team at LUTH performed the first simulation of our entire observable Universe, from the Big Bang to the present day -- equivalent to 90 billion light years (7). Beyond employing the standard cosmological model using the cosmological constant, they developed two additional cosmological models taking into account dark energy (4), a mysterious component introduced to explain the accelerating expansion of the Universe (5).

What is the imprint of dark energy on the structure of the Universe? And conversely, how can the structure of the Universe be tied to the nature of this energy? These are two fundamental questions that project DEUS project is attempting to answer.

The simulation using the standard model of cosmology, which has just been completed, has already measured the number of clusters of galaxies (144 million) to be of a mass greater than one hundred thousand billion solar masses. The research suggests that the first cluster of this type appeared when the Universe was only 2 billion years and the most massive cluster today now weighs 15 million billion solar masses.

The calculations are also designed to measure changes in the distribution of dark matter. The fluctuations in the cosmic background radiation from the Big Bang have been observed by the WMAP and Planck satellites. These observations were reflected by the simulation, which covers the entire history of the Universe with unprecedented accuracy and on the broadest range of scales ever attempted. According to the results, they accurately reveal the fingerprints of Dark Matter on primordial gas ("Baryon Acoustic Oscillations"). These results represent important new knowledge for the entire cosmological community.

The simulation results from all three cosmological models are expected to be complete by May 2012. Not only will the work help to better understand the influence of dark energy on the structure of the Universe, but it can also be used to support and interpret cosmological "catalogs" collected from various observational projects, in particular, those developed by major international space agencies, such as project EUCLID (8). EUCLID is supported by ESA, the European Space Agency.

The implementation of DEUS was made possible thanks to the powerful resources available to the researchers by GENCI (6), most notably, CURIE, a supercomputer with more than 92,000 processors and capable of achieving 2 million billion operations per second (2 petaflops). The system is installed and operated by CEA at the TGCC facility, in Bruyères-le-Châtel. Designed by Bull, CURIE is currently one of the five most powerful such machines in the world.

The DEUS - Full Universe Run work goes well beyond the calculations acheived by international teams at other large-scale computing centers. The project will require more than 30 million hours of computing (nearly 3500 years), using almost all the CURIE processors. More than 150 petabytes of data (the equivalent of 30 million DVDs) will be generated during these calculations. That data will be filtered down to a single petabyte to be stored.

(1) The LUTE is a laboratory Observatoire de Paris / CNRS / Université Paris Diderot and a scientific department of the Paris Observatory.

(2) DEUS: Universe Dark Energy Simulation, www.deus-consortium.org

(3) Jean-Michel Alimi, Pier-Stefano Corasaniti, Yann Rasera, Irene Balmes, Bouillot Vincent, Vincent Reverdy.

(4) The first model is a concordance model, based on the cosmological constant. A second model predicts the presence of a dynamic component of dark energy that fills the entire Universe. The third model simulates a modification to the law of gravity at large scales, by taking into account an accelerator component known as phantom energy.

(5) The observational work that implied cosmic dark energy could be accelerating the expansion of the universe was awarded the Nobel Prize for Physics in 2011.

(6) www.genci.fr

(7) In a Universe age of about 13.7 billion years, light travels to reach us a distance greater than 13.7 billion light-years due to the expansion of the Universe. This distance depends precisely model cosmological considered. Space is expanding it expands during the trip and leads the light to travel about 45 billion light years.

(8) EUCLID is one of the missions of the Cosmic Vision program of ESA (period 2015-2025). EUCLID is devoted to the study of cause of the the acceleration in the expanding Universe. http://www.esa.int/esaSC/SEMOZ59U7TG_index

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Source: based on press release from DEUS Consortium