Evolution of cosmic filaments and of their galaxy population from MHD cosmological simulations

TL;DR

This study uses cosmological simulations to analyze how the physical and magnetic properties of cosmic filaments depend on mass and redshift, and compares simulated galaxy populations within filaments to observational data.

Contribution

It provides the first statistical correlations between filament properties and mass, and compares simulated galaxy distributions with GAMA survey observations.

Findings

Filament temperature, length, volume, and magnetic field are tightly correlated with mass.

Simulated and observed filaments of the same length contain similar numbers of galaxies.

Galaxy properties within filaments can predict the gas characteristics of the large-scale structure.

Abstract

Despite containing about a half of the total matter in the Universe, at most wavelengths the filamentary structure of the cosmic web is difficult to observe. In this work, we use large unigrid cosmological simulations to investigate how the geometrical, thermodynamical and magnetic properties of cosmological filaments vary with mass and redshift (z $\leq 1$). We find that the average temperature, length, volume and magnetic field of filaments are tightly log-log correlated with the underlying total gravitational mass. This reflects the role of self-gravity in shaping their properties and enables statistical predictions of their observational properties based on their mass. We also focus on the properties of the simulated population of galaxy-sized halos within filaments, and compare their properties to the results obtained from the spectroscopic GAMA survey. Simulated and observed filaments with the same length are found to contain an equal number of galaxies, with very similar distribution of halo masses. The total number of galaxies within each filament and the total/average stellar mass in galaxies can now be used to predict also the large-scale properties of the gas in the host filaments across tens or hundreds of Mpc in scale. These results are the first steps towards the future use of galaxy catalogues in order to select the best targets for observations of the warm-hot intergalactic medium.