Related papers: Luminosity distance-redshift relation for the LTB …
We propose two efficient numerical methods of evaluating the luminosity distance in the spatially flat {\Lambda}CDM universe. The first method is based on the Carlson symmetric form of elliptic integrals, which is highly accurate and can…
A validation of the cosmic distance duality (CDD) relation, eta(z)=(1+z)^2 d_A(z)/d_L(z)=1, coupling the luminosity (d_L) and angular-diameter (d_A) distances, is crucial because its violation would require exotic new physics. We present a…
The notion of distance between a global Maxwellian function and an arbitrary solution $f$ (with the same total density $\rho$ at the fixed moment $t$) of Boltzmann equation is introduced. In this way we essentially generalize the important…
The Cosmic Distance Duality Relation (CDDR) is a basic relation of standard cosmology. This work tests the CDDR and cosmic transparency using angular diameter distances from DESI DR2, luminosity distances from Pantheon+, and direct…
The distance-duality relation (DDR) between the luminosity distance $D_L$ and the angular diameter distance $D_A$ is viewed as a powerful tool for testing for the opacity of the Universe, being independent of any cosmological model. It was…
We find a solution to Einstein field equations for a regular toroidal lattice of size L with equal masses M at the centre of each cell; this solution is exact at order M/L. Such a solution is convenient to study the dynamics of an assembly…
We compute the cosmic star formation rate (SFR) and the rest-frame comoving luminosity density in various pass-bands as a function of redshift using large-scale \Lambda-CDM hydrodynamical simulations with the aim of understanding their…
The relation between the central mass and quasar luminosity (M_BH \propto L^{\alpha}FHWM^2) links a given Eddington ratio with a value of H_0, within a cosmology with fixed (\Omega_m,\Omega_{\Lambda}). We point out that because the relation…
In this paper, we obtain an alternative expression for the distance of a function in $BLO$ from the subspace $L^\infty$. The distance is the one induced by choosing a new "norm" on $BLO$, equivalent to the usual one and that has the…
In this letter, the distance-duality (DD) relation is reconstructed by Gaussian process (GP) which is cosmological model-independent. Generally, the GP plays two important roles. One is to shape the $\eta$ tendency which denotes the…
A new class of solutions of Einstein's equations is derived providing a physically plausible hydrodynamic description of cosmological matter in the radiation era of the Universe expansion. The solutions are characterized by the LTB metric…
We use our catalog of photometric redshifts in the Hubble Deep Field (HDF) to estimate the Luminosity Function (LF) of galaxies up to z=2. Using the obtained LF and a relationship between luminosity and halo size, we calculate the expected…
By the use of homotopy perturbation method-Pad\'e (HPM-Pad\'e) technique, a new analytical approximation of luminosity distance in the flat universe is proposed, which has the advantage of significant improvement for accuracy in…
A single impurity in the 1D Luttinger model creates a local modification of the charge density analogous to the Friedel oscillations. In this paper, we present an exact solution of the case $g={1\over 2}$ (the equivalent of the Toulouse…
In this paper, we consider the inverse source problem for the time-fractional diffusion equation, which has been known to be an ill-posed problem. To deal with the ill-posedness of the problem, we propose to transform the problem into a…
The recent analysis of low-redshift supernovae (SN) has increased the apparent tension between the value of $H_0$ estimated from low and high redshift observations such as the cosmic microwave background (CMB) radiation. At the same time…
This work proposes and analyzes a fully discrete numerical scheme for solving the Landau-Lifshitz-Gilbert (LLG) equation, which achieves fourth-order spatial accuracy and third-order temporal accuracy.Spatially, fourth-order accuracy is…
Solving the Stefan problem, also referred as the heat conduction problem with phase change, is a necessary step to solve phase change problems with convection. In this article, we are interested in using the Lattice Boltzmann Method (LBM)…
The relation between angular diameter distance and redshift in a spherically symmetric dust-shell universe is studied. This model has large inhomogeneities of matter distribution on small scales. We have discovered that the relation agrees…
We consider two main inverse Sturm-Liouville problems: the problem of recovery of the potential and the boundary conditions from two spectra or from a spectral density function. A simple method for practical solution of such problems is…