Voids in the simulated local Universe

Abstract

We use simulations of the formation and evolution of the galaxy population in the local Universe to address the issue of whether the standard theoretical model succeeds in producing empty regions as large and as dark as those observed nearby. We follow the formation of galaxies in a cold dark matter universe and work with mock catalogues that can resolve the morphology of Large Magellanic Cloud sized galaxies, and the luminosity of objects six times fainter. We look for a void signature in sets of virialized haloes selected by mass, and in mock galaxy samples selected according to observationally relevant quantities, such as luminosity, colour or morphology. We find several void regions with diameter 10 h −1 Mpc in the simulation where gravity seems to have swept away even the smallest haloes we were able to track. We probe the environment density for the various populations and compute luminosity functions for galaxies residing in underdense, mean density and overdense regions. We also use nearest-neighbour statistics to check possible void populations, taking L * spirals as reference neighbours. Down to our resolution limits, we find that all types of galaxies avoid the same regions, and that no class appears to populate the voids defined by the bright galaxies.

Cosmic Voids: Structure, Dynamics and Galaxies

“…68,86,24,115,33,16,71 In recent years the huge increase in computational resources has enabled N-body simulations to resolve in detail the intricate substructure of voids within the context of hierarchical cosmological structure formation scenarios. 70,34,46,2,33,16,71 They confirm the theoretical expectation of voids having a rich substructure as a result of their hierarchical buildup (see e.g. Fig.…”

Cosmology with a dynamically screened scalar interaction in the dark sector

“…The first question is put to the test in [20], who use the nearest neighbor statistic that is applied to the observations in [3]. The conclusion in [20] is that the predicted distribution shows little sensitivity to the halo mass, consistent with what is observed.…”

“…But if departures from linearity in m ± (φ) arise from dimension 5 operators like (φ 2 /M Pl )Ψ + Ψ + , then we do need y s n s /y + n + > 1 to lock φ. With the cosmological parameters in (20) and (21), equations (18) and (22) with (23) give…”

“…The observational situation is reviewed in [3]. It may be compared to the distribution of dark matter halos in the numerical N-body simulation shown in figure 1 in [20]. In the simulation there are relatively large dark matter halos that might be suitable homes for the normal galaxies -with masses comparable to the Milky Way -that contain most of the visible stars.…”

The Void Galaxy Survey

“…Box 800, 9700AV Groningen, the Netherlands e-mail: weygaert@astro.rug.nl emphasized by Peebles [25], this dearth of dwarf void galaxies cannot be straightforwardly understood in our standard Λ CDM based view of galaxy formation: voids are expected to be teeming with dwarfs and low surface brightness galaxies. Various astrophysical processes, ranging from gas and radiation feedback processes to environmental properties of dark matter halos, have been suggested [25,22,15,11,34]. The issue is, however, far from solved and progress will depend largely on new observations that characterize void galaxies and their immediate environment.…”