Stellar and dark matter density in the Local Universe

TL;DR

This study estimates the distribution of luminous and dark matter in the local universe using galaxy group catalogs, revealing that most dark matter resides outside virialized structures.

Contribution

It provides new measurements of stellar and total matter densities across different scales in the local universe using recent all-sky galaxy group data.

Findings

Mean stellar density within 11 Mpc is 0.44% of critical density.

Total matter density within 11 Mpc is 0.17 of critical density.

Dark matter predominantly exists outside virialized galaxy groups.

Abstract

We calculate the mean density profiles for luminous and dark matter on distance scales $D \sim(1 - 100)$ Mpc around us using recent all-sky catalogs of galaxy groups. Within the Local Volume $( D < 11 ~\rm Mpc)$ we derived the mean stellar density $\Omega_*= 0.44\%$ in the critical density units and the mean total matter density $\Omega_m = 0.17$. In the sphere with a radius of 40 Mpc these quantities drop to $\Omega_* = 0.24 - 0.32\%$ and $\Omega_m = 0.09 - 0.14$. In a larger volume within $D\sim135$ Mpc the discussed densities become more uncertain: $\Omega_* = 0.20 - 0.24\%$ and $\Omega_m = 0.05 - 0.16$. We summarize that the major part of the cosmic dark matter locates outside the virial and collapsing zones of groups and clusters.