Non-Friedmann cosmology for the Local Universe, significance of the universal Hubble constant, and short-distance indicators of dark energy

Abstract

Based on the increasing evidence of the cosmological relevance of the local Hubble flow, we consider a simple analytical cosmological model for the Local Universe. This is a non-Friedmann model with a non-uniform static space-time. The major dynamical factor controlling the local expansion is the antigravity produced by the omnipresent and permanent dark energy of the cosmic vacuum (or the cosmological constant). The antigravity dominates at larger distances than 1-2 Mpc from the center of the Local group. The model gives a natural explanation of the two key quantitative characteristics of the local expansion flow, which are the local Hubble constant and the velocity dispersion of the flow. The observed kinematical similarity of the local and global flows of expansion is clarified by the model. We analytically demonstrate the efficiency of the vacuum cooling mechanism that allows one to see the Hubble law this close to the Local group. The "universal Hubble constant" H V (≈60 km s −1 Mpc −1 ), depending only on the vacuum density, has special significance locally and globally. The model makes a number of verifiable predictions. It also unexpectedly shows that the dwarf galaxies of the local flow with the shortest distances and lowest redshifts may be the most sensitive indicators of dark energy in our neighborhood.

Local dark matter and dark energy as estimated on a scale of ~1 Mpc in a self-consistent way

“…From recent CMB studies (Spergel et al 2007), ρ v ≈ 7 × 10 −30 g cm −1 . In earlier studies, using the HST observations of the local Hubble cell (Karachentsev 2005;Karachentsev et al 2003Karachentsev et al -2009, we found that the density of dark energy can be studied independently of the global measurements (Chernin 2001;Chernin et al 2006;Teerikorpi et al 2008). We concluded that a local dark energy density of the global value ρ v and a group mass from the literature are consistent with the local Hubble cell ∼1 Mpc dynamics.…”

“…The radical difference in the phase-space structure of the group and the outflow around it is the most prominent feature of the local Hubble cell. We have argued earlier (Chernin et al 2000(Chernin et al , 2006Chernin 2001;Teerikorpi et al 2008) that the physics behind this feature might be due to the interplay between the gravity of the group and antigravity of the dark energy background, so that the group size is less than R v and the flow starts at the distances R > R v (as in the example above). Therefore the zero-gravity surface is located somewhere in the gap between the group and the outflow in the distance interval of 1.2-1.6 Mpc.…”

“…The antigravity force produced by the dark energy density ρ v is given by Einstein's linear law (e.g. Chernin 2001Chernin et al 2006) in the same reference frame:…”

The Hubble diagram for a system within dark energy: the location of the zero-gravity radius and the global Hubble rate

“…What happens at larger distances depends on whether the local model is still valid -one finally reaches the distance R M which gives the size of the volume from which the mass M has been gathered during the formation of the group (so-called Einstein-Straus vacuole; Chernin et al 2006). One can calculate the present radius R M of the region from which the mass M was gathered, assuming the present average cosmic mass den-…”

“…Dark energy can be studied locally (Chernin et al 2006;Teerikorpi et al 2008), as its "antigravity" can affect galaxy motions near us in a volume a few Mpc across (Chernin et al 2003). Also, the real mass of a system can only be found if the dark energy is included, because gravitating systems "lose" a part of their gravity due to the antigravity of the dark energy within them (Chernin et al 2009).…”