Revealing the Dark Threads of the Cosmic Web

Abstract

Modern cosmology predicts that matter in our Universe has assembled today into a vast network of filamentary structures colloquially termed the Cosmic Web. Because this matter is either electromagnetically invisible (i.e., dark) or too diffuse to image in emission, tests of this cosmic web paradigm are limited. Wide-field surveys do reveal web-like structures in the galaxy distribution, but these luminous galaxies represent less than 10% of baryonic matter. Statistics of absorption by the intergalactic medium (IGM) via spectroscopy of distant quasars support the model yet have not conclusively tied the diffuse IGM to the web. Here, we report on a new method inspired by the Physarum polycephalum slime mold that is able to infer the density field of the Cosmic Web from galaxy surveys. Applying our technique to galaxy and absorption-line surveys of the local Universe, we demonstrate that the bulk of the IGM indeed resides in the Cosmic Web. From the outskirts of Cosmic Web filaments, at approximately the cosmic mean matter density (ρ m ) and ∼ 5 virial radii from nearby galaxies, we detect an increasing H i absorption signature towards higher densities and the circumgalactic medium, to ∼ 200ρ m . However, the absorption is suppressed within the densest environments, suggesting shock-heating and ionization deep within filaments and/or feedback processes within galaxies.

Monte Carlo Physarum Machine: Characteristics of Pattern Formation in Continuous Stochastic Transport Networks

“…This section briefly summarizes the existing work in this domain. For more details, please refer to the comprehensive survey by Libeskind et al (2018), as well as our prior work (Burchett et al, 2020;Simha et al, 2020).…”

“…The second contribution is the case study applying MCPM to data sets whose geometric complexity is higher than that of optimal transport networks but still resembles them to a large degree, especially with regard to their topology. Here we study the fitting process and reconstruction results using a task-specific variant of MCPM (section 6), which we have previously applied in the context of cosmological modeling and visualization (Burchett et al, 2020;Simha et al, 2020). We demonstrate how the probabilistic form of MCPM benefits the task of reconstructing the cosmic web, the structural features of which are best described by a density field, rather than a network in the strict sense (section 7).…”

Cosmic voids and filaments from quantum gravity

“…There is a strong correlation between the original t-foliation (color) and new time coordinate ψ t (horizontal axis) tures of voids and filaments observed in our real Universe (see e.g. [16]; the plots can be found on the web [17,18]). Using the new coordinates, we observe a pattern of volume concentrations in the spatial directions.…”

Visualization in Astrophysics: Developing New Methods, Discovering Our Universe, and Educating the Earth

“…Researchers can update the simulation at interactive rates by a wide range of adjusting model parameters. Polyphorm has been used to reconstruct the cosmic web from galaxy observations [BET∗20] and to infer the ionized intergalactic medium contribution to the dispersion measure of a fast radio burst [SBP∗20].…”