Initial Conditions to Cosmological N-Body Simulations, or, How to Run an Ensemble of Simulations

By E. Sirko. 2005

150 citations recorded by the source corpus.

The conventional method of generating initial conditions for cosmological N-body simulations introduces a significant error in the real-space statistical properties of the particles. More specifically, the finite box size leads to a significant underestimate of σ8, the correlation function, and nonlinear effects. I implement a method of generating initial conditions for N-body simulations that accurately models the real-space statistical properties, such as the mass variance in spheres and the correlation function. The method requires running ensembles of simulations because the power in the DC mode is no longer assumed to be zero. For moderately sized boxes, I demonstrate that the new method corrects the underestimate in the mass variance in spheres and the shape of the correlation function. I also argue that subtracting Poisson noise from the power spectrum is a dangerous practice. Code to generate initial conditions to second order in Lagrangian perturbation theory with the new method is available from the author.

Subfields: Astronomy and Astrophysics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/6df8e0f25edd8f118df8b73088c16028b1de73e5

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Statistical and Nonlinear Physics

Citations in the corpus

The halo mass function from the dark ages through the present day (2006, methodology): “While these techniques are able to account for the missing large-scale power, they do not account for cosmic variance, i.e. the run-to-run variations introduced by the finite sampling of density modes, particularly at scales near the box size (e.g. Sirko 2005).”
Virial Scaling of Massive Dark Matter Halos: Why Clusters Prefer a High Normalization Cosmology (2007, background): “Numerical Resolution Simulations of randomcosmic volumes have the benefit of producing statistical samples of halos that are unbiased in the large volume limit, and can be made so by appropriate mode sampling of finite-volume realizations (Sirko 2005).”
Multi-scale initial conditions for cosmological simulations (2011, methodology): “Sirko (2005) has shown conclusively that this conventional method can lead to a significant error in the real-space statistical properties, in particular for small cosmological box sizes.”
The halo mass function through the cosmic ages (2012, background): “There is therefore a disconnect that needs to be bridged between simulations and an ideal, global mass function (Sirko 2005; Bagla & Prasad 2006; Power & Knebe 2006).”
Resolving cosmic structure formation with the Millennium-II simulation (2009, methodology): “We have not performed a shot noise correction in this figure, as it not clear that it is appropriate to do so (see, e.g., Baugh et al. 1995; Sirko 2005).”
Galaxies–intergalactic medium interaction calculation – I. Galaxy formation as a function of large-scale environment (2009, background): “…limitation of relatively small volumes is that fluctuations on scales comparable to the size of the box become non-negligible at a relatively high redshift (Bagla & Ray 2005; Sirko 2005), after which the simulation can no longer be considered a faithful representation of the underlying model.”
Transients from initial conditions in cosmological simulations (2006, background): “…of the ZA has been essentially taken for granted and instead studies of initial conditions have concentrated on other (important) issues, related to how to best implement the ZA in different situations (Bertschinger 1995; Salmon 1996; Pen 1997; Bertschinger 2001; Yoshida et al. 2003; Sirko 2005).”
Efficient Simulations of Early Structure Formation and Reionization (2007, methodology): “…velocity field corresponding to our linear density field using the standard Zel’Dovich approximation (c.f. Zel’Dovich 1970; Efstathiou et al. 1985; Sirko 2005): x1 =x + ψ(x) , (4) v≡ ẋ1 = ψ̇(x) , (5) δ(x)=−∇·[(1 + δ(x))ψ(x)] ≈−∇ · ψ(x) , (6) where x and x1 denote initial (Lagrangian) and…”
The MassiveBlack-II simulation: The evolution of haloes and galaxies to z ~ 0 (2014, background): “This is a well-known effect (Bagla & Ray 2005; Sirko 2005; Bagla & Prasad 2006) and masses can be corrected by accounting for the missing power (Reed et al. 2007; Watson et al. 2013).”