Galactos: Computing the Anisotropic 3-Point Correlation Function for 2 Billion Galaxies

Abstract

The nature of dark energy and the complete theory of gravity are two central questions currently facing cosmology. A vital tool for addressing them is the 3-point correlation function (3PCF), which probes deviations from a spatially random distribution of galaxies. However, the 3PCF's formidable computational expense has prevented its application to astronomical surveys comprising millions to billions of galaxies. We present Galactos, a high-performance implementation of a novel, O(N^2) algorithm that uses a load-balanced k-d tree and spherical harmonic expansions to compute the anisotropic 3PCF. Our implementation is optimized for the Intel Xeon Phi architecture, exploiting SIMD parallelism, instruction and thread concurrency, and significant L1 and L2 cache reuse, reaching 39% of peak performance on a single node. Galactos scales to the full Cori system, achieving 9.8PF (peak) and 5.06PF (sustained) across 9636 nodes, making the 3PCF easily computable for all galaxies in the observable universe.

11 pages, 7 figures, accepted to SuperComputing 2017

References in corpus (19)

• Dynamics of dark energy
• The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological analysis of the DR12 galaxy sample
• Observational Probes of Cosmic Acceleration
• Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Power Spectra and WMAP-Derived Parameters
• Cosmic Growth History and Expansion History
• Relative velocity of dark matter and baryonic fluids and the formation of the first structures
• Clustering of dark matter tracers: generalizing bias for the coming era of precision LSS
• The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: RSD measurement from the power spectrum and bispectrum of the DR12 BOSS galaxies
• The Skewness of the Aperture Mass Statistic
• The Bispectrum as a Signature of Gravitational Instability in Redshift-Space
• Cosmology and the Bispectrum
• The power spectrum and bispectrum of SDSS DR11 BOSS galaxies I: bias and gravity
• Density Studies of MHD Interstellar Turbulence: Statistical Moments, Correlations and Bispectrum
• Computing the Three-Point Correlation Function of Galaxies in $\mathcal{O}(N^2)$ Time
• The Effect of Large-Scale Structure on the SDSS Galaxy Three-Point Correlation Function
• Fast Algorithms and Efficient Statistics: N-point Correlation Functions
• Three-Point Correlation Functions of SDSS Galaxies: Constraining Galaxy-Mass Bias
• Redshift distortions of galaxy correlation functions
• Lagrangian perturbations and the matter bispectrum II: the resummed one-loop correction to the matter bispectrum

Cited by in corpus (5)

• nbodykit: an open-source, massively parallel toolkit for large-scale structure
• Measurement of Parity-Odd Modes in the Large-Scale 4-Point Correlation Function of SDSS BOSS DR12 CMASS and LOWZ Galaxies
• Testing the theory of gravity with DESI: estimators, predictions and simulation requirements
• Optimal computation of anisotropic galaxy three point correlation function multipoles using 2DFFTLOG formalism
• Workflow environments for advanced cyberinfrastructure platforms