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Baryonic Acoustic Oscillation Visualization

Visualization Credits: Amit Chourasia

Data Simulation Credits: Robert Harkness, Mike Norman, and Pascal Paschos

A UCSD team consisting of Michael Norman, Robert Harkness, and Pascal Paschos has used NERSC Seaborg to carry out the largest simulation of the IGM to date. The simulation follows the growth of density perturbations in both gas and dark matter components in a volume 1 billion light years on a side beginning shortly after the Big Bang and evolved to half the present age of the universe, where comparisons with observations are best made. The simulation calculates the gravitational clumping of intergalactic gas and dark matter modeled using a computational grid of 8 billion cells and 8 billion dark matter particles, making it the largest simulation of its kind.

The principal scientific goal of this project was to see whether a phenomenon known as baryon acoustic oscillations (BAO) is detectable in the intergalactic absorption. BAO are wiggles in the cosmic plasma laid down in the early universe and were recently detected in the cosmic microwave background temperature anisotropies by the WMAP satellite. Detection of BAO in the large scale distribution of galaxies and the IGM at later cosmic times would provide astronomers with a new tool to investigate cosmic dark energy. The wavelength of the BAO oscillation is about 1000 times the wavelength of the typical matter fluctuations which give rise to the observed intergalactic absorption features. This large range of length scales dictated the size of the computational grid, which is 2048^3 cells. The UCSD team has months of data analysis ahead of them before they can say whether such a measurement is possible. The analysis will be carried out at the San Diego Supercomputer Center.

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Large scale structure of the intergalactic medium at z=1.
Projections of 2048x2048x2048 data
density
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density

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