相关论文: The angular size - redshift relation in power-law …
It is well known that anthropic selection from a landscape with a flat prior distribution of cosmological constant Lambda gives a reasonable fit to observation. However, a realistic model of the multiverse has a physical volume that…
The dependence of Brans-Dicke (BD) parameter upon the scalar field, for different cosmological era of the expanding universe, has been explored. The time dependence of the scalar field has been determined and thereby the explicit time…
In this paper, we consider a cosmological model in $ f(R, G) $ gravity in a flat space-time, where $ R $ is the Ricci scalar and $ G $ is the Gauss-Bonnet invariant. The function $ f(R, G) $ is taken as a linear combination of $ R $ and an…
This article presents a simple model that reproduces key concepts of modern cosmology within the framework of special relativity, at a level that is suitable for an undergraduate or high school setting. The model includes cosmic expansion…
The accelerated expansion of the universe is a rather established fact in cosmology and many different models have been proposed as a viable explanation. Many of these models are based on the standard general relativistic framework of…
We present a new simple functional form to model the evolution of a spherical mass distribution in a cosmological context. Two parameters control the growth of the system and this is modelled using a redshift dependent exponential for the…
The weak lensing shear signal has been measured numerically in $N$-body simulations at 14 different redshifts ($z_s = 0.1$ to 3.6) and on angular scales of $\theta = 2'$ to 32'. In addition, the data have been validated by analytical…
We report the finding of a scaling relation among the cosmic-web anisotropy parameter $A$, the linear density rms fluctuation sigma(r) and the linear growth factor D(z). Using the tidal field derived from the Millennium Simulation on…
We take into account redshift-space distortion measurements to investigate the growth of cosmological large-scale structures within the framework of modified symmetric teleparallel $f(Q)$ gravity. After comparing the predictions of the…
The redshift-space distortion (RSD) in the observed distribution of galaxies is known as a powerful probe of cosmology. Observations of large-scale RSD have given tight constraints on the linear growth rate of the large-scale structures in…
Under the assumption that the gas mass fraction of galaxy clusters estimated out to an outer hydrostatic radius is constant, it is possible to constrain the cosmological parameters by using the angular diameter distance relation with…
The quantum model of the homogeneous and isotropic universe predicts logarithmic-law dependence of coordinate distance to source on redshift z which is in good agreement with type Ia supernovae and radio galaxies observations for the…
We discuss how the space of possible cosmological parameters is constrained by the angular diameter distance function, D_A(z), as measured using the SZ/X-ray method which combines Sunyaev-Zel'dovich (SZ) effect and X-ray brightness data for…
A strictly linear evolution of the cosmological scale factor is surprisingly an excellent fit to a host of cosmological observations. Any model that can support such a coasting presents itself as a falsifiable model as far as classical…
We use the Simon, Verde, & Jimenez (2005) determination of the redshift dependence of the Hubble parameter to constrain cosmological parameters in three dark energy cosmological models. We consider the standard $\Lambda$CDM model, the XCDM…
Of all the distance and temporal measures in cosmology, the angular-diameter distance, d_A(z), uniquely reaches a maximum value at some finite redshift z_max and then decreases to zero towards the big bang. This effect has been difficult to…
The present paper reports a study on the dimensionless parameter $\omega$ in Brans-Dicke theory. Based on a particular choice of scale factor $a$, we have investigated the signature flip of the deceleration parameter $q$ to see whether the…
We discuss how the redshift dependence of the observed two-point correlation function of various classes of objects can be related to theoretical predictions. This relation involves first a calculation of the redshift evolution of the…
The large-scale structure growth index $\gamma$ provides a consistency test of the standard cosmology and is a potential indicator of modified gravity. We investigate the constraints on $\gamma$ from next-generation spectroscopic surveys,…
We have investigated the cosmological scenarios with a four dimensional effective action which is connected with multidimensional, supergravity and string theories. The solution for the scale factor is such that initially universe undergoes…