Simulating structure formation of the Local Universe
Abstract
In this work, we present cosmological Nbody simulations of the Local Universe with initial conditions constrained by the 2MASS Redshift Survey (2MRS) within a cubic volume of 180 h^{1} Mpc sidelength centred at the Local Group. We use a selfconsistent Bayesianbased approach to explore the joint parameter space of primordial density fluctuations and peculiar velocity fields, which are compatible with the 2MRS galaxy distribution after cosmic evolution. This method (the KIGEN code) includes the novel augmented Lagrangian perturbation theory (LPT) structure formation model which combines secondorder LPT (2LPT) on large scales with the spherical collapse model on small scales. Furthermore, we describe coherent flows with 2LPT and include a dispersion term to model fingers of god (fogs) arising from virialized structures. These implementations are crucial to avoid artificial parallel filamentary structures, which appear when using the structure formation model with the 2LPT approximation and the data with compressed fogs. We assume Λ CDM cosmology throughout our method. The recovered initial Gaussian fields are used to perform a set of 25 constrained simulations. Statistically, this ensemble of simulations is in agreement with a reference set of 25 simulations based on randomly seeded Gaussian fluctuations in terms of matter statistics, power spectra and mass functions. Considering the entire volume of (180 h^{1} Mpc)^{3}, we obtain correlation coefficients of about 98.3 per cent for the celltocell comparison between the simulated density fields and the galaxy density field in log space with Gaussian smoothing scales of r_{S} = 3.5 h^{1} Mpc (74 per cent for r_{S} = 1.4 h^{1} Mpc). The cross power spectra show correlations with the galaxy distribution which weakens towards smaller lengthscales until they vanish at scales of 2.23.0 h^{1} Mpc. The simulations we present provide a fully nonlinear density and velocity field with a high level of correlation with the observed galaxy distribution at scales of a few Mpc.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 November 2013
 DOI:
 10.1093/mnras/stt1428
 arXiv:
 arXiv:1304.6565
 Bibcode:
 2013MNRAS.435.2065H
 Keywords:

 methods: numerical;
 catalogues;
 galaxies: clusters: general;
 galaxies: statistics;
 largescale structure of Universe;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 accepted by MNRAS