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

Abstract

Context. Dark energy was first detected from large distances on gigaparsec scales. If it is vacuum energy (or Einstein's Λ), it should also exist in very local space. Here we discuss its measurement on megaparsec scales of the Local Group. Aims. We combine the modified Kahn-Woltjer method for the Milky Way-M 31 binary and the HST observations of the expansion flow around the Local Group in order to study in a self-consistent way and simultaneously the local density of dark energy and the dark matter mass contained within the Local Group. Methods. A theoretical model is used that accounts for the dynamical effects of dark energy on a scale of ∼1 Mpc. Results. The local dark energy density is put into the range 0.8−3.7ρ v (ρ v is the globally measured density), and the Local Group mass lies within 3.1−5.8 × 10 12 M . The lower limit of the local dark energy density, about 4/5× the global value, is determined by the natural binding condition for the group binary and the maximal zero-gravity radius. The near coincidence of two values measured with independent methods on scales differing by ∼1000 times is remarkable. The mass ∼4 × 10 12 M and the local dark energy density ∼ρ v are also consistent with the expansion flow close to the Local Group, within the standard cosmological model. Conclusions. One should take into account the dark energy in dynamical mass estimation methods for galaxy groups, including the virial theorem. Our analysis gives new strong evidence in favor of Einstein's idea of the universal antigravity described by the cosmological constant.

Dark energy domination in the Virgocentric flow

“…The zero-gravity radius of the Virgo system is about 10 times larger than that of the Local system for which R ZG = 1−1.3 Mpc Chernin et al 2000Chernin et al , 2009. We see here the same factor 10 as for the phase structures of the Virgo and Local systems (Sect.…”

“…Local dynamical effects of dark energy have been studied by Chernin et al (2000Chernin et al ( , 2009, , Baryshev et al (2001), Karachentsev et al (2003a), Byrd et al (2007), and Teerikorpi et al (2008). For the Local Group and the outflow close to it, we showed that the antigravity produced by the dark energy background exceeds the gravity of the group at distances beyond 1.5 Mpc from the group barycenter.…”

On Öpik’s distance evaluation method in a cosmological context

“…(3)) used above does not contain any local dark energy term, which would in all cases have a minor effect on systems smaller than galaxy groups (Chernin et al 2009). …”

A graph of dark energy significance on different spatial and mass scales

“…In a weak field situation one may A&A 577, A144 (2015) write (Chernin et al 2009) the force affecting a test particle with mass m as the sum of Newton's gravity force produced by the mass M and Einstein's antigravity force due to DE:…”

“…In regions where the DE dominates the gravitating matter, new structures do not condense and linear perturbations of density decay (or even nonlinear, if sheet-like; Chernin et al 2003). The antigravity of DE also puts an upper limit on the size of a bound system of a certain mass, and it influences dynamic mass determinations, leading to too low a mass Chernin et al (2009Chernin et al ( , 2012.…”