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The cosmological mean matter (dark and baryonic) density measured in the units of the critical density is Ω m = 0.27. Independently, the local mean density is estimated to be Ω loc = 0.08−0.23 from recent data on galaxy groups at redshifts up to z = 0.01−0.03 (as published by Crook et al. 2007, ApJ, 655, 790 and Makarov & Karachentsev 2011, MNRAS, 412, 2498. If the lower values of Ω loc are reliable, as Makarov & Karachentsev and some other observers prefer, does this mean that the Local Universe of 100-300 Mpc across is an underdensity in the cosmic matter distribution? Or could it nevertheless be representative of the mean cosmic density or even be an overdensity due to the Local Supercluster therein. We focus on dark matter halos of groups of galaxies and check how much dark mass the invisible outer layers of the halos are able to host. The outer layers are usually devoid of bright galaxies and cannot be seen at large distances. The key factor which bounds the size of an isolated halo is the local antigravity produced by the omnipresent background of dark energy. A gravitationally bound halo does not extend beyond the zero-gravity surface where the gravity of matter and the antigravity of dark energy balance, thus defining a natural upper size of a system. We use our theory of local dynamical effects of dark energy to estimate the maximal sizes and masses of the extended dark halos. Using data from three recent catalogs of galaxy groups, we show that the calculated mass bounds conform with the assumption that a significant amount of dark matter is located in the invisible outer parts of the extended halos, sufficient to fill the gap between the observed and expected local matter density. Nearby groups of galaxies and the Virgo cluster have dark halos which seem to extend up to their zero-gravity surfaces. If the extended halo is a common feature of gravitationally bound systems on scales of galaxy groups and clusters, the Local Universe could be typical or even an overdense region, with a low density contrast ∼1.

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“…1 Equation (8) comes from the Schwarzschild-de Sitter spacetime in weak field approximation (see, e.g., Chernin et al , 2008.…”

Section: The Isothermal Halomentioning

confidence: 99%

Dark energy and extended dark matter halos

Chernin

Teerikorpi

Valtonen

et al. 2012

A&A

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“…Effects of gravitational self-catching should be typical for Universe. The existence of "Hubble boxes" is discussed in review [4] as typical blocks of the nearby Universe. Gravitational self-catching takes place for Big Bang having given birth to the global expansion of Universe, but also for Little Bang in so called Local Group (using the Hubble's terminology) of galaxies.…”

Section: Hubble Expansion and The Problem Of Dark Energymentioning

confidence: 99%

“…The inescapable conclusion, assuming that Newton's law of gravity (and the local physics description) holds on cosmological scales, that the visible galaxy was embedded in a much larger dark matter (DM) halo, which contributes roughly 50% -90% of the total mass of a galaxy. As result another models of gravitation were involved in consideration-from "improved" Newtonian laws (such as modified Newtonian dynamics and tensorvector-scalar gravity [3]) to the Einstein's theory based on the cosmological constant [4]. Einstein introduced this term as a mechanism to obtain a stable solution of the gravitational field equation that would lead to a static Universe, effectively using dark energy to balance gravity.…”

Section: Introductionmentioning

confidence: 99%

To the Theory of Galaxies Rotation and the Hubble Expansion in the Frame of Non-Local Physics

Alexeev¹

2012

JMP

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The unified generalized non-local theory is applied for mathematical modeling of cosmic objects. For the case of galaxies the theory leads to the flat rotation curves known from observations. The transformation of Kepler's regime into the flat rotation curves for different solitons is shown. The Hubble expansion with acceleration is explained as result of mathematical modeling based on the principles of non-local physics. Peculiar features of the rotational speeds of galaxies and effects of the Hubble expansion need not in the introduction of new essence like dark matter and dark energy. The origin of difficulties consists in the total Oversimplification following from the principles of local physics.

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“…A transition to the Newtonian limit, where DE is described by the anti-gravity force in vacuum, was made by Chernin (2008).…”

Section: Newtonian Approximation In Description Of Dementioning

confidence: 99%

“…It was shown by Chernin (2001Chernin ( , 2008 that outer parts of galaxy clusters may be under strong influence of dark energy (DE), which was discovered by observations of supernovae (SN) Ia at redshift z ≤ 1 (Riess et al 1998;Perlmutter et al 1999) and in the spectrum of fluctuations of cosmic microwave background (CMB) radiation (see e.g. Spergel et al 2003;Tegmark et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Galaxy clusters in presence of dark energy: a kinetic approach

Merafina

Бисноватый-Коган

Donnari

2014

A&A

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Context. The external regions of galaxy clusters may be under strong influence of the dark energy, which was discovered by observations of supernovae Ia at redshift z < 1. The presence of the dark energy in the gravitational equilibrium equation, with the Einstein Λ term, balances the gravity, and extends the equilibrium configuration more in radius. Aims. We investigate the features of the equilibrium configurations to analyse how the presence of the dark energy affects the density profiles and radial extension by specifying the conditions for which the gravitational equilibrium begins. Methods. We derived the kinetic equation for an equilibrium configuration in presence of dark energy and solved the gravitational equilibrium equation by considering a Maxwell-Boltzmann distribution function with a cut-off in the framework of the Newtonian regime, because the observed velocities of galaxies inside a cluster are much lower than the velocity of light.Results. The prevalence of dark energy effects on the gravity shows a wide region in the W 0 -ρ Λ diagram where equilibrium solutions are not possible. In these particular conditions, the galaxies located in the external regions of a cluster can flow out, following the accelerating expansion of the Universe.

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Cited by 105 publications

References 43 publications

Dark energy and extended dark matter halos

Dark energy and extended dark matter halos

To the Theory of Galaxies Rotation and the Hubble Expansion in the Frame of Non-Local Physics

Galaxy clusters in presence of dark energy: a kinetic approach

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