As the largest gravitationally bound structures known, clusters provide clear constraints on the formation of structure and on the composition of the universe. Despite their extreme importance for cos-mology the number of clusters at high redshift (z>0.75) is rather small. There are only a few X-ray emitting examples reported and a handful of optically-selected ones. These clusters can provide ...

Astronomical observations in the electromagnetic window – microwave, radio and optical – have revealed that most of the Universe is dark. The only reason we know that dark matter exists is because of its gravitational influence on luminous matter. It is plausible that a small fraction of that dark matter is clumped, and strongly gravitating. Such systems are potential sources of gravitational r...

In this paper we have tried to describe a gauge group for gravitational potential associated with the elementary particle as described by their spiral structure in accordance with the standard model. It relates to the framework of quantum field theory considering the Dark Potential Waves which constitutes the Universe to be destructively interfering through Symmetry which breaks spontaneously t...

We estimate the possible variations of the gravitational constant G in the framework of a generalized (BergmannWagoner-Nordtvedt) scalar-tensor theory of gravity on the basis of the field equations, without using their special solutions. Specific estimates are essentially related to the values of other cosmological parameters (the Hubble and acceleration parameters, the dark matter density etc....

The Machian cosmological solution satisfying φ = O(ρ/ω) for the perfect-fluid with negative pressure is discussed. When the coefficient of the equation of state γ → −1/3, the gravitational constant approaches to constant. If we assume the present mass density ρ0 ∼ ρc (critical density), the parameter ǫ (γ = (ǫ− 1)/3) has a value of order 10−3 to support the present gravitational constant. The c...

introduction: wavelet transform is one of the useful and suitable tools for time series and signal analysis. nowadays wavelet transform is frequently used in geophysical data processing and interpretation, especially seismic data. however, the use of this method isn’t widespread in gravity and geomagnetic. fedi and quarta (1998), martelet et al. (2001) and de oliveira lyrio (2004) used the wave...

According to the gravitational suppression (GraS) hypothesis the gravitational interaction between exotic (dark) and standard (visible) matter is suppressed below the kpc scales. We review the phenomenological motivations at the basis of this idea and its formal implementation by means of a Yukawa contribution to the usual Newtonian potential. We also discuss a class of astrophysical phenomena ...

We discuss the influence of gravitational effects on the stabilization of the chromomagnetic vacuum. The one-loop effective potential for a covariantly constant SU(2) gauge field in S2 × R2 and T2 × R2 is calculated. A possibility of curvature-induced phase transitions between zero and nonzero chromomagnetic vacua is found —what is also confirmed through the calculation of the renormalization g...

The quantum gravity is formulated based on gauge principle. The model discussed in this paper has local gravitational gauge symmetry and gravitational field is represented by gauge potential. A preliminary study on gravitational gauge group is presented. Path integral quantization of the theory is discussed in the paper. A strict proof on the renormalizability of the theory is also given. In le...

We present new weak lensing observations of 1E0657−558 (z = 0.296), a unique cluster merger, that enable a direct detection of dark matter, independent of assumptions regarding the nature of the gravitational force law. Due to the collision of two clusters, the dissipationless stellar component and the fluid-like X-ray emitting plasma are spatially segregated. By using both wide-field ground ba...