Solving large scale structure in ten easy steps with COLA

We present the COmoving Lagrangian Acceleration (COLA) method: an N-body method for solving for Large Scale Structure (LSS) in a frame that is comoving with observers following trajectories calculated in Lagrangian Perturbation Theory (LPT). Unlike standard N-body methods, the COLA method can straig...

Full description

Saved in:
Bibliographic Details
Published in:Journal of cosmology and astroparticle physics 2013-06, Vol.2013 (6), p.1-18
Main Authors: Tassev, Svetlin, Zaldarriaga, Matias, Eisenstein, Daniel J
Format: Article
Language:English
Subjects:
Acceleration
ACCURACY
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
C CODES
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
COSMOLOGY
Dynamics
GAIN
GALAXY CLUSTERS
GRAVITATIONAL LENSES
Halos
LAGRANGIAN FUNCTION
MASS
Mathematical analysis
PERTURBATION THEORY
Small scale
STATISTICS
VELOCITY
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We present the COmoving Lagrangian Acceleration (COLA) method: an N-body method for solving for Large Scale Structure (LSS) in a frame that is comoving with observers following trajectories calculated in Lagrangian Perturbation Theory (LPT). Unlike standard N-body methods, the COLA method can straightforwardly trade accuracy at small-scales in order to gain computational speed without sacrificing accuracy at large scales. This is especially useful for cheaply generating large ensembles of accurate mock halo catalogs required to study galaxy clustering and weak lensing, as those catalogs are essential for performing detailed error analysis for ongoing and future surveys of LSS. As an illustration, we ran a COLA-based N-body code on a box of size 100Mpc/h with particles of mass approximately 5 x 10 super(9)M[odot]/h. Running the code with only 10 timesteps was su cient to obtain an accurate description of halo statistics down to halo masses of at least 10 super(11)M[odot]/h . This is only at a modest speed penalty when compared to mocks obtained with LPT. A standard detailed N-body run is orders of magnitude slower than our COLA-based code. The speed-up we obtain with COLA is due to the fact that we calculate the large-scale dynamics exactly using LPT, while letting the N-body code solve for the small scales, without requiring it to capture exactly the internal dynamics of halos. Achieving a similar level of accuracy in halo statistics without the COLA method requires at least 3 times more timesteps than when COLA is employed.
ISSN:1475-7516
1475-7516
DOI:10.1088/1475-7516/2013/06/036