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About This GigapanToggle
- Taken by
- Yu Feng
- Explore score
- 1166.40 Gigapixels
- Date added
- Apr 30, 2011
- Date taken
- Apr 30, 2011
This image, the first one of terapixel size uploaded to the GigaPan website was created by Yu Feng and Rupert Croft (McWilliams Center for Cosmology, Carnegie Mellon University, www.cmu.edu/cosmology ) from a hydrodynamic supercomputer simulation of cosmic structure using the P-Gadget code carried out by Tiziana Di Matteo, Nishikanta Khandai, Rupert Croft, Volker Springel, Anirban Jana and Jeff Gardner. The creation of the GigaPan from the image was carried out by Yu Feng and Randy Sargent, Paul Heckbert and Paul Dille (Robotics Institute, CMU). The black hole histories were computed by Colin Degraf and Julio Lopez (CMU). The black hole snapshots were made by Lily Scherlis (Phillips Academy, Andover).
Cosmology has a "Standard Model", which includes the Big Bang, Inflation, and Dark Matter. With this framework, we can use computer simulations to understand how structures form, how the action of gravity amplifies initially tiny perturbations, giving rise to galaxies, stars and black holes. Here we have used a supercomputer to evolve a model universe forwards in time, subject to the laws of physics which have been included: gravity, gas dynamics, radiative cooling, black hole physics and more. Our analytical theories of how astrophysical processes take place can be checked with these numerical experiments, which also provide predictions to be compared with observational data.
The simulation shown here is known as "MassiveBlack" and was run using the cosmological hydrodynamics code "P-GADGET" using all 100,000 compute cores of the Cray XT5 supercomputer "Kraken" at the National Institute for Computational Sciences [*]. The simulation is of the so called "LambdaCDM" cosmology  and was run in a box of side length 533/h comoving Megaparsecs using 2x3200^3 particles, or 65 billion particles in total.
To make the image, the simulation box was unfolded into a slice 5 billion light years wide and 6 million light years thick. Each pixel in the image represents an area of 3000x3000 light years. As a reference, the diameter of the Milky Way is about 15000 light years. The time represented in the image is redshift z=4.75, when the universe is 1.3 billion years old (compare to the current age of universe of 13.6 billion years.) Having already passed through the 'Dark Ages' due to the recombination of nuclei with electrons, the universe at this moment is transparent, and most quasars and stars are ready to be observed.
One of the main goals of the simulation is to study how supermassive black holes form and grow in the early universe and how they feed of cosmic gas to become quasars, light sources that can be a hundred trillion times the brightness of the Sun.
Shown in red/yellow is the density of atomic matter (the dark matter, which makes up most of the mass in the universe is not shown, but has a similar structure). As one zooms in the filamentary gaseous structures are revealed. The deep blue shows the regions with high star formation rate, the regions where the atomic matter is so concentrated that stars are formed. The green circles identify the black holes, with larger circles for more massive black holes (the very largest ones have masses a billion times that of the Sun or more). The white dots represent the distribution of star particles, with each dot representing millions of stars.
Snapshots have been taken of significant objects that have formed in the simulation.
The set of 10 snapshots are those of the 10 most massive black holes. Super massive black holes reside in galaxies. These black holes 'eat' the atomic matter, and give out radiation in the form of light, heating the surrounding environment.
More details of the simulation are given in Di Matteo et al. 2011 (link to be posted soon). See also arxiv.org/abs/astro-ph/0505010 , arxiv.org/abs/0705.2269
This work was supported by allocations of advanced computing resources provided by the National Science Foundation, and by award NSF OCI-0749212 and AST-1009781. The simulation was performed on Kraken at the National Institute for Computational Sciences[*]. The visualization was carried out on BlackLight, at the Pittsburgh Supercomputing Center [**], Warp, provided by the Moore foundation, in the Bruce and Astrid McWilliams Center for Cosmology at CMU [***]. Development was carried out using the McWilliams eScience Video Facility at CMU.
 See, eg, www.wolframalpha.com/input/?i=cosmology+redshift+z%3D4.75
[*] www.nics.tennessee.edu /
[**] www.psc.edu , www.teragrid.org