Bolshoi (simulation)

Bolshoi (simulation)
Name	Bolshoi
First release	2011
Language	English
Operating system	Linux
License	Proprietary / public data products

Bolshoi (simulation) The Bolshoi simulation is a large-scale cosmological N-body simulation of dark matter structure formation commissioned to model the evolution of the Universe from early conditions consistent with the Wilkinson Microwave Anisotropy Probe and Planck measurements. It was produced by a collaboration involving researchers at institutions including the Kavli Institute for Particle Astrophysics and Cosmology, Leiden University, and New Mexico State University, using initial conditions informed by the Lambda-CDM model, the Cosmic Microwave Background, and parameters constrained by Type Ia supernova surveys and Baryon Acoustic Oscillations. The project aimed to provide high-resolution predictions for the distribution of dark matter halos relevant to studies by surveys such as Sloan Digital Sky Survey, DESI, and LSST.

Overview and objectives

The Bolshoi project was designed to resolve the formation and evolution of dark matter halos and subhalos across cosmic time to inform interpretations of observations from Hubble Space Telescope, Spitzer Space Telescope, Chandra X-ray Observatory, and ground-based facilities like Keck Observatory and Very Large Telescope. Objectives included producing halo catalogs for comparison with galaxy surveys such as SDSS, DEEP2 Galaxy Redshift Survey, and 2dF Galaxy Redshift Survey, testing predictions of the Lambda-CDM model against alternatives like Warm dark matter scenarios, and enabling semi-analytic modeling linked to projects at Max Planck Institute for Astrophysics and Institute for Advanced Study.

Simulation design and methodology

Bolshoi employed a particle-based N-body technique using a force solver and time integration scheme developed by teams at KIPAC and collaborators linked to Los Alamos National Laboratory and Princeton University. The simulation used cosmological parameters calibrated to measurements from WMAP and later compared with Planck results, initializing perturbations from a transfer function computed with codes used by groups at CITA and Columbia University. Halo identification used algorithms related to Friends-of-Friends and spherical overdensity methods comparable to those developed at University of California, Berkeley and University of Michigan, while merger trees were generated in formats compatible with pipelines at Harvard-Smithsonian Center for Astrophysics and Space Telescope Science Institute.

Computational resources and data products

Bolshoi required petascale memory and compute resources provided by supercomputers at national centers including National Energy Research Scientific Computing Center, Oak Ridge National Laboratory, and facilities associated with Argonne National Laboratory. The final datasets included multi-terabyte particle snapshots, halo catalogs, and merger trees used by researchers at Princeton, Stanford University, and University of Chicago. Public data releases were curated with interfaces inspired by archives at NASA Ames Research Center and IPAC, and adopted metadata standards related to efforts at International Virtual Observatory Alliance and NASA/IPAC Extragalactic Database for access by teams at Yale University and University of Cambridge.

Key scientific results

Analyses of Bolshoi outputs led to quantitative predictions for halo mass functions and concentration–mass relations tested against results from groups at Max Planck Society, University of California, Santa Cruz, and Rutgers University. The simulation provided constraints on subhalo abundance matching techniques used by researchers at University of Washington and Columbia, clarified the statistics of halo merger rates explored by teams at University of Toronto and University of Pennsylvania, and informed models of galaxy clustering relevant to projects at Imperial College London and ETH Zurich. Bolshoi results were cited in studies addressing small-scale challenges to Lambda-CDM raised by investigators at Oxford University and University of Barcelona, and used to interpret strong-lensing anomalies studied by groups at Caltech and Max Planck Institute for Astronomy.

Comparison with other cosmological simulations

Bolshoi is often compared with contemporaneous simulations such as the Millennium Simulation produced by the Max Planck Institute for Astrophysics, the Illustris project from MIT and MPIA, and later efforts like EAGLE from ICC, Durham and Horizon-AGN from CEA Saclay. Compared to Millennium, Bolshoi used updated cosmological parameters reflecting WMAP/Planck constraints and achieved higher mass resolution similar to efforts at University of California, Santa Cruz and Carnegie Mellon University, while lacking the full hydrodynamics of Illustris and EAGLE undertaken by teams at KIPAC and MPIA. Its merger-tree catalogs complemented semi-analytic models developed at Max Planck Institute and empirical models pursued at Johns Hopkins University.

Legacy, usage, and access details

Bolshoi data products have been incorporated into analysis pipelines at institutions such as Rutgers University, University of Toronto, University of California, Berkeley, and Princeton University, supporting hundreds of publications by researchers at Harvard University, Caltech, and University of Oxford. Access to public catalogs and tools followed practices established by archives at NASA, ESA, and the International Astronomical Union, enabling use by survey collaborations including SDSS, DESI, and LSST Science Collaboration. The Bolshoi legacy persists in successor simulations and methodological frameworks adopted by groups at Flatiron Institute and Perimeter Institute for ongoing investigations into structure formation.

Category:Cosmological simulations