Voids in the distribution of galaxies and the Cosmological constant

Cosmological Black Holes

In this paper we propose a model for the formation of the cosmological voids. We show that cosmological voids can form directly after the collapse of extremely large wavelength perturbations into low-density black holes or cosmological black holes (CBH). Consequently the voids are formed by the comoving expansion of the matter that surrounds the collapsed perturbation. It follows that the universe evolves, in first approximation, according to the Einstein-Straus cosmological model. We discuss finally the possibility to detect the presence of these black holes through their weak and strong lens…

The Galaxy Population In Voids: Are All Voids The Same?

The influence of under-dense environments on the formation and evolution of galaxies is studied by analysing the photometric properties of ~200 galaxies residing in voids, taken from our SDSS DR10 void catalogue up to z ~0.055. We split void galaxies into two subsamples based on the luminosity density contrast of their host voids: 'sparse void' δ_s = δ < -0.95 and 'populous void' δ_p = δ > -0.87. We find that galaxies in sparse voids are less massive than galaxies in populous voids. The luminosity distribution of galaxies in populous voids follows the same distribution observed across the SDSS…

Void alignment and density profile applied to measuring cosmological parameters

We study the orientation and density profiles of the cosmological voids with SDSS10 data. Using voids to test Alcock-Paczynski effect has been proposed and tested in both simulations and actual SDSS data. Previous observations imply that there exist an empirical stretching factor which plays an important role in the voids' orientation. Simulations indicate that this empirical stretching factor is caused by the void galaxies' peculiar velocities. Recently Hamaus et al. found that voids' density profiles are universal and their average velocities satisfy linear theory very well. In this article …

$Λ$ effect in the cosmological expansion of voids

The dynamical effect of the cosmological constant $Λ$ on a single spherical void evolving in a the universe is investigated within a non linear perturbation of Newton-Friedmann models. The void expands with a huge initial burst which freezes asymptotically with time up to matching Hubble flow. For $Ω_{\circ}\sim 0.3$, $Λ$-effect on the kinematics intervenes significantly by amplifying the expansion rate at redshift $z\sim 1.7$. As a result, the size increases with the background density and with $Λ$, what interprets by the gravitational attraction of borders from outside regions and the gravit…

On the role of shear in cosmological averaging II: large voids, non-empty voids and a network of different voids

We study the effect of shear on the cosmological backreaction in the context of matching voids and walls together using the exact inhomogeneous Lemaitre-Tolman-Bondi solution. Generalizing JCAP 1010 (2010) 021, we allow the size of the voids to be arbitrary and the densities of the voids and walls to vary in the range 0 < Omega_v < Omega_w < 1. We derive the exact analytic result for the backreaction and consider its series expansion in powers of the ratio of the void size to the horizon size, r_0/t_0. In addition, we deduce a very simple fitting formula for the backreaction with error less th…

宇宙空洞与动力学分析. IV. 哈勃张力与宇宙学常数

Cosmic voids and the kinetic analysis. IV. Hubble tension and the cosmological constant

本文用Vlasov动力学方法研究晚期宇宙结构形成，通过引入含宇宙学常数斥力项的引力势解决哈勃张力，并解释空洞与墙结构的形成机制。