Fake dark matter from retarded distortions

We push ahead the idea developed in a previous work, that some fraction of the dark matter and the dark energy can be explained as a relativistic effect. The inhomogeneity matter generates gravitational distortions, which are general relativistically retarded. These combine in a magnification effect since the past matter density, which generated the distortion we feel now, is greater than the present one. The non negligible effect on the averaged expansion of the universe contributes both to the estimations of the dark matter and to the dark energy, so that the parameters of the Cosmological Standard Model need some corrections. In this second work we apply the previously developed framework to relativistic models of the universe. It results that one parameter remain free, so that more solutions are possible, as function of inhomogeneity. One of these fully explains the dark energy, but requires more dark matter than the Cosmological Standard Model ($$91\%$$ 91 % of the total matter). Another solution fully explains the dark matter, but requires more dark energy than the Cosmological Standard Model ($$15\%$$ 15 % more). A third noteworthy solution explains a consistent part of the dark matter ($$63\%$$ 63 % of the total matter) and also some of the dark energy ($$4\%$$ 4 % ).

Estimating Galactic Dark Matter and Redshift in Flat Space Cosmology

With reference to known galactic rotation speeds and previous publications on our light-speed expanding Flat Space Cosmology model, a toy model variation is presented herein for the purpose of exploring possible time-dependent relationships between galactic dark matter, visible matter, total matter, redshift, radius and angular velocity. The result of this exploration, in the form of graphs and tables, provides for remarkable correlations with current galactic observations and perhaps moves us closer to understanding the scalar nature and influence of dark matter and Lambda on the expanding universe. With reference to light speed expansion, if one is willing to re-define cosmic red shift as [z/(1+z)], without considering Lambda cosmology inputs, light travel distances can be reproduced with a marginal error of +8.6% at z =1.2, (i.e. traditional light travel distance is 8.6% higher than our estimate), 0% at z = 11.5 and -5.5% at z = 1200.( i.e. traditional light travel distance is 5.5% lower than our estimate).

Optimal void finders in weak lensing maps

ABSTRACT Cosmic voids are a key component of the large-scale structure that contain a plethora of cosmological information. Typically, voids are identified from the underlying galaxy distribution, which is a biased tracer of the total matter field. Previous works have shown that 2D voids identified in weak lensing (WL) maps – WL voids – correspond better to true underdense regions along the line of sight. In this work, we study how the properties of WL voids depend on the choice of void finder, by adapting several popular void finders. We present and discuss the differences between identifying voids directly in the convergence maps, and in the distribution of WL peaks. Particular effort has been made to test how these results are affected by galaxy shape noise (GSN), which is a dominant source of noise in WL observations. By studying the signal-to-noise ratios (S/N) for the tangential shear profile of each void finder, we find that voids identified directly in the convergence maps have the highest S/N but are also the ones most affected by GSN. Troughs are least affected by noise, but also have the lowest S/N. The tunnel algorithm, which identifies voids in the distribution of WL peaks, represents a good compromise between finding a large tangential shear S/N and mitigating the effect of GSN.

An adapted filter function for density split statistics in weak lensing

Context. The density split statistics in weak gravitational lensing analyses probes the correlation between regions of different (foreground) galaxy number densities and their weak lensing signal, which is measured by the shape distortion of background galaxies. Aims. In this paper, we reconsider density split statistics, by constructing a new angular filter function that is adapted to the expected relation between the galaxy number density and shear pattern, in a way that the filter weighting the galaxy number density is matched to the filter that is used to quantify the shear signal. Methods. We used the results of numerical ray-tracing simulations, specifically through the Millennium Simulation supplemented by a galaxy distribution based on a semi-analytic model, to construct a matched pair of adapted filter functions for the galaxy density and the tangential shear signal. We compared the performance of our new filter to the previously used top-hat filter, applying both to a different and independent set of numerical simulations (SLICS, cosmo-SLICS). Results. We show that the adapted filter yields a better correlation between the total matter and the galaxy distribution. Furthermore, the adapted filter provides a larger signal-to-noise ratio to constrain the bias between the total matter and the galaxy distribution, and we show that it is, in general, a more sensitive discriminator between different cosmologies, with the exception of cosmologies with very large σ8 values. All analyses lead to the conclusion that our adapted filter should be favoured in future density split statistic works.

The intracluster light as a tracer of the total matter density distribution: a view from simulations

ABSTRACT By using deep observations of clusters of galaxies, it has been recently found that the projected stellar mass density closely follows the projected total (dark and baryonic) mass density within the innermost ∼140 kpc. In this work, we aim to test these observations using the Cluster-EAGLE simulations, comparing the projected densities inferred directly from the simulations. We compare the iso-density contours using the procedure of Montes & Trujillo, and find that the shape of the stellar mass distribution follows that of the total matter even more closely than observed, although their radial profiles differ substantially. The ratio between stellar and total matter density profiles in circular apertures shows a slope close to −1, with a small dependence on the cluster’s total mass. We propose an indirect method to calculate the halo mass and mass density profile from the radial profile of the intracluster stellar mass density.

On the road to per cent accuracy – III. Non-linear reaction of the matter power spectrum to massive neutrinos

ABSTRACT We analytically model the non-linear effects induced by massive neutrinos on the total matter power spectrum using the halo model reaction framework of Cataneo et al. In this approach, the halo model is used to determine the relative change to the matter power spectrum caused by new physics beyond the concordance cosmology. Using standard fitting functions for the halo abundance and the halo mass–concentration relation, the total matter power spectrum in the presence of massive neutrinos is predicted to per cent-level accuracy, out to $k=10 \,{ h}\,{\rm Mpc}^{-1}$. We find that refining the prescriptions for the halo properties using N-body simulations improves the recovered accuracy to better than 1 per cent. This paper serves as another demonstration for how the halo model reaction framework, in combination with a single suite of standard Λ cold dark matter (ΛCDM) simulations, can recover per cent-level accurate predictions for beyond ΛCDM matter power spectra, well into the non-linear regime.

An Outline Picture of a Growing and Rotating Planck Universe with Emerging Dark Foam

With reference to Planck scale, Mach’s relation, increasing support for large scale cosmic anisotropy and preferred directions and by introducing two new parameters Gamma and Beta, right from the beginning of Planck scale, we make an attempt to estimate ordinary matter density ratio, dark matter density ratio, mass, radius, temperature, age and expansion velocity (from and about the bay universe in all directions). We would like suggest that, from the beginning of Planck scale, 1) Dark matter can be considered as a kind of cosmic foam responsible for formation of galaxies. 2) Cosmic angular velocity is directly proportional to squared cosmic temperature. 3) Cosmic expansion velocity increases with decreasing total matter density ratio. 4) There is no need to consider dark energy for understanding cosmic acceleration.

Gamma and Beta Model of Growing and Rotating Planck Ball

With reference to Planck scale, Mach’s relation, increasing support for large scale cosmic anisotropy & preferred directions and by introducing two new parameters Gamma and Beta, right from the beginning of Planck scale, we make an attempt to estimate ordinary matter density ratio, dark matter density ratio, mass, radius, temperature, age and expansion velocity (from and about the Planck mass in all directions). By considering H 0 ≅70 km/sec/Mpc, estimated current cosmic mass, radius, total matter density, expansion velocity, temperature and age are: 4.3352 × 1053 kg, 3.207 × 1026 m, 3.138 × 10−27 kg·m−3, 2.43c, 2.721 K and 19.78 Billion years  respectively. Point to be noted is that, with reference to Planck scale, ratio of Hubble parameter Ht to angular velocity ωt can be expressed with ( H t / ω t )≅ γ t ≅[ 1+ln( H pl / H t ) ]≅ 3 H t 2 c 2 / 8πG( a T t 4 ) where Hpl represents Planck scale angular velocity and ( a T t 4 ) is the thermal energy density. ( H 0 / ω 0 )≅ γ 0 ≅141.26 and ω 0 ≅1.606× 10 −20  rad/sec≅5.068× 10 −13  rad/year.  It needs further study. Proceeding further, from the beginning of Planck scale, a) With a ‘decreasing’ trend of total matter density ratio, cosmic expansion velocity can be shown to be increasing. b) With an ‘increasing’ trend of total matter density ratio, cosmic expansion velocity can be shown to be decreasing. c) With a constant trend of total matter density ratio, cosmic expansion velocity can be shown to be constant. In this model, in understanding the currently believed cosmic acceleration, there is no need to consider dark energy.

On the Eternal Role of Planck Scale in Machian Cosmology

With reference to Planck scale, Mach's relation and by introducing two new parameters Gamma and Beta, right from the beginning of Planck scale, we make an attempt to estimate ordinary matter density ratio, dark matter density ratio, mass, radius, temperature, age and expansion velocity (from and about the Planck mass in all directions). In analogy with currently believed cosmic acceleration, with a decreasing trend of total matter density ratio, cosmic expansion velocity can be shown to be increasing. By considering H 0 ≅ 70 km/sec/Mpc, estimated current cosmic mass, radius, total matter density, expansion velocity, temperature and age are: 4.3352 × 10 53   kg , 3.207 × 10 26   m , 3.138 × 10 − 27   kg . m - 3 , 2.43 c , 2.721   K and 19.78   Billion   years respectively. Point to be noted is that, with reference to Planck scale, cosmic temperature seems to be redshifted by a factor ( Z T ) t ≅ 1 + ln ( H p l / H t ) − 1 where ( H p l , H t ) represent Planck scale and time dependent Hubble parameters respectively. As a peculiar case, considering the equality of current Hubble parameter and current angular velocity, current cosmic rotational kinetic energy can be estimated to be 0.667 times the current critical energy. It needs further study.

Technical issues in a spherical system coupled with isotropic matter distribution and the horizon problem with higher curvature quantities

In this paper, we explore some technical issue in the study of a spherical system coupled with isotropic matter distribution. We also study the horizon problem under the influence of higher curvature quantities. We evaluate well-known equations of motion. We also join the exterior region with an interior one by taking the well-known matching conditions. We first find total matter content within the system and then calculate black hole and cosmological horizons. We have developed a technique for determining some dynamical variables that are involved in controlling the time duration of the emergence of horizons as well as singularities.