Topology of large scale under-dense regions

TL;DR

This study analyzes the large-scale distribution of matter using quasars from SDSS DR7, identifying large voids and examining their properties and effects on CMB temperature, contributing to understanding cosmic large-scale structure.

Contribution

It presents a new void finding algorithm and provides statistical analysis of void sizes, shapes, and their impact on CMB temperature using quasar data.

Findings

More large voids are found than in random distributions.

Largest voids exceed 300 Mpc in diameter.

CMB temperature is slightly lower in directions of large voids.

Abstract

We investigate the large scale matter distribution adopting QSOs as matter tracer. The quasar catalogue based on the SDSS DR7 is used. The void finding algorithm is presented and statistical properties of void sizes and shapes are determined. Number of large voids in the quasar distribution is greater than the number of the same size voids found in the random distribution. The largest voids with diameters exceeding 300 Mpc indicate an existence of comparable size areas of lower than the average matter density. No void-void space correlations have been detected, and no larger scale deviations from the uniform distribution are revealed. The average CMB temperature in the directions of the largest voids is lower than in the surrounding areas by 0.0046 +/- 0.0028 mK. This figure is compared to the amplitude of the expected temperature depletion caused by the Integrated Sachs-Wolfe effect.