Properties of Cosmological Filaments extracted from Eulerian Simulations

Abstract

Using a new parallel algorithm implemented within the VisIt framework, we analysed large cosmological grid simulations to study the properties of baryons in filaments. The procedure allows us to build large catalogues with up to $\sim 3 \cdot 10^4$ filaments per simulated volume and to investigate the properties of cosmic filaments for very large volumes at high resolution (up to $300^3 ~\rm Mpc^3$ simulated with $2048^3$ cells). We determined scaling relations for the mass, volume, length and temperature of filaments and compared them to those of galaxy clusters. The longest filaments have a total length of about $200 ~\rm Mpc$ with a mass of several $10^{15} M_{\odot}$. We also investigated the effects of different gas physics. Radiative cooling significantly modifies the thermal properties of the warm-hot-intergalactic medium of filaments, mainly by lowering their mean temperature via line cooling. On the other hand, powerful feedback from active galactic nuclei in surrounding halos can heat up the gas in filaments. The impact of shock-accelerated cosmic rays from diffusive shock acceleration on filaments is small and the ratio of between cosmic ray and gas pressure within filaments is of the order of $\sim 10-20$ percent.