The Initial Conditions of the Universe from Constrained Simulations

By Francisco-Shu Kitaura. 2012

92 citations recorded by the source corpus.

I present a new approach to recover the primordial density fluctuations and the cosmic web structure underlying a galaxy distribution. The method is based on sampling Gaussian fields which are compatible with a galaxy distribution and a structure formation model. This is achieved by splitting the inversion problem into two Gibbs-sampling steps: the first being a Gaussianisation step transforming a distribution of point sources at Lagrangian positions -which are not a priori given- into a linear alias-free Gaussian field. This step is based on Hamiltonian sampling with a Gaussian-Poisson model. The second step consists on a likelihood comparison in which the set of matter tracers at the initial conditions is constrained on the galaxy distribution and the assumed structure formation model. For computational reasons second order Lagrangian Perturbation Theory is used. However, the presented approach is flexible to adopt any structure formation model. A semi-analytic halo-model based galaxy mock catalog is taken to demonstrate that the recovered initial conditions are closely unbiased with respect to the actual ones from the corresponding N-body simulation down to scales of a ~ 5 Mpc/h. The cross-correlation between them shows a substantial gain of information, being at k ~ 0.3 h/Mpc more than doubled. In addition the initial conditions are extremely well Gaussian distributed and the power-spectra follow the shape of the linear power-spectrum being very close to the actual one from the simulation down to scales of k ~ 1 h/Mpc.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

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Citations in the corpus

Learning to predict the cosmological structure formation (2018, methodology): “2LPT is used in many cosmological analyses to generate a large number of cosmological simulations for comparison of astronomical dataset against the physical model (59, 60) or to compute the covariance of the dataset (61– 63).”
Tracing the cosmic web (2017, background): “…al. 2014; Schaye et al. 2015) and recent Bayesian reconstructions of the underlying dark matter distribution in the Local Universe (Heß et al. 2013; Kitaura 2013; Nuza et al. 2014; Leclercq et al. 2015b; Sorce et al. 2016), we have come to realize that the weblike pattern is even more pronounced…”
FastPM: a new scheme for fast simulations of dark matter and haloes (2016, methodology): “…(Knebe et al. 2015), to vary the predictions as a function of cosmological or nuisance parameters (for example, galaxy formation parameters in halo occupation models as by Cooray & Sheth 2002), or even as a tool to generate initial conditions (Wang et al. 2013; Jasche & Wandelt 2013; Kitaura 2013).”