Constrained simulations of the local universe: I. Mass and motion in the Local Volume

Abstract

It has been recently claimed that there is no correlation between the distribution of galaxies and their peculiar velocities within the Local Volume (LV), namely a sphere of R=7/h Mpc around the Local Group (LG). It has been then stated that this implies that either locally dark matter is not distributed in the same way as luminous matter, or peculiar velocities are not due to fluctuations in mass. To test that statement a set of constrained N-body cosmological simulations, designed to reproduce the main observed large scale structure, have been analyzed. The simulations were performed within the flat-Lambda, open and flat matter only CDM cosmogonies. Two unconstrained simulations of the flat-Lambda and open CDM models were performed for comparison. LG-like objects have been selected so as to mimic the real LG environment. The local gravitational field due to all halos found within each LV is compared with the exact gravitational field induced by all matter in the simulation. We conclude that there is no correlation between the exact and the local gravitational field obtained by pairwise newtonian forces between halos. Moreover, the local gravitational field is uncorrelated with the peculiar velocities of halos. The exact gravitational field has a linear correlation with peculiar velocities but the proportionality constant relating the velocity with gravitational field falls below the prediction of the linear theory. Upon considering all matter inside the LVs, the exact and local gravitational accelerations show a much better correlation, but with a considerable scatter independent on the cosmological models. The main conclusion is that the lack of correlation between the local gravitation and the peculiar velocity fields around LG-like objects is naturally expected in the CDM cosmologies.

arXiv comment10 pages, 19 figures. Accepted for publication in MNRAS

References in corpus (18)

• The cosmological simulation code GADGET-2
• The SBF Survey of Galaxy Distances. IV. SBF Magnitudes, Colors, and Distances
• The Mass Function of an X-Ray Flux-Limited Sample of Galaxy Clusters
• Galaxies in N-body simulations: overcoming the overmerging problem
• Resolving the Structure of Cold Dark Matter Halos II
• The evolution substructure I: a new identification method
• Homogeneous Velocity-Distance Data for Peculiar Velocity Analysis. III. The Mark III Catalog of Galaxy Peculiar Velocities
• Constrained Simulations of the Real Universe: II. Observational Signatures of Intergalactic Gas in the Local Supercluster Region
• The Local Group and other neighboring galaxy groups
• Constrained Simulations of the Real Universe: the Local Supercluster
• Wiener Reconstruction of Large-Scale Structure from Peculiar Velocities
• Simulating the Formation of the Local Galaxy Population
• The Local Group as a test of cosmological models
• The imprints of local superclusters on the Sunyaev-Zel'dovich signals and their detectability with Planck
• Gravitational Instability of Cold Matter
• The signature of dark energy on the local Hubble flow
• Shear Fields and the Evolution of Galactic-Scale Density Peaks
• Light and Motion in the Local Volume

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• The Local Hubble Flow: Is it a Manifestation of Dark Energy?
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• Constrained simulations of the local universe: II. The nature of the local Hubble flow
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• The kinematical center and mass profile of the Local Group