Collections : [Lyrasis Special Collections]

Scope and Contents note

The project files consists of data in three broad categories: the simulation data ("Data at Redshift" components); analysis tools and example scripts (Data Processing Tools) for processing the data; and project administration and background documents (Historical Documents) related to the project. All these materials were created between 2005 and 2012, beginning with a proposal for the LUSciD Project, continuing on to the simulation data, and ending with the recent analysis tools. The historical documents are proposals and progress reports that were part of grants or requests for computational resources supporting the research. The component for analysis tools and example scripts contains the source code to yt (http://yt-project.org/), which was used to produce the example data analysis results. The results are a combination of structured text, binary files, and images. The historical documents and analysis tools are described in greater detail in their component descriptions.

The scientific motivations for the light cone simulation are described in the Project Background. Here we describe how the simulation data was generated. The simulation was the final in a group of simulations, with each one designed to meet certain requirements, such as resolution. Earlier simulations tied to the LUsciD Project were performed on Thunder, a Lawrence Livermore National Laboratory cluster. This calculation for the Santa Fe Light Cone Simulation was a demonstration of the software's ability to perform adaptive refinement throughout the volume, and as a result, was run on the San Diego Supercomputer Center's DataStar system and the National Center for Supercomputing Applications Altix, Cobalt.

The simulation was initialized at high redshift, assuming a standard cosmological model incorporating dark energy and cold dark matter. The physical volume represented was a periodic cube 512 comoving megaparsecs on a side. The simulation was evolved to the present day, using models for gravity and adiabatic gas dynamics. At specific points, snapshots of the simulation were saved, and a representative subset of those are contained in this collection.

These snapshots are organized by time (or, equivalently, redshift) at the top level, and named from RD0009 to RD0036; lower numbers (e.g., RD0009) represent earlier times in the universe's evolution, while higher numbers are later times and ones closer to the present day. Each snapshot has an archive (tar) file of the original data, a checksum of the archive, and text files of the parameters, grid hierarchy, and boundary conditions. The parameter, hierarchy, and boundary files are also in the archive file, but are available separately for convenience in a component named "Parameters."

The contents of each project component labeled RD00## are the same:

* RD00## (parameters, ASCII): All of the simulation parameters are listed in these files as key-value pairs, using a "key = value" format. The input parameter are identical across all parameter files, while variables such as the current time, or redshift, change.

* RD00##.hierarchy (grid metadata, ASCII): A list of the grid data structures, their spatial position, file names, and numerical size.

* RD00##.cpu0XXX (physical data, HDF5): These files hold the physical fields (density, velocity, etc.) for each grid.

* RD00##.boundary (boundary conditions, ASCII): Boundary metadata.

* RD00##.boundary.hdf (boundary conditions, HDF5): Boundary data for necessary fields