AI Insight
This study uses FLAMINGO simulations to investigate how massive neutrinos alter the large-scale structure of the universe, specifically the cosmic web's distribution of voids, sheets, filaments, and clusters. The researchers found that increasing neutrino mass decreases the volume occupied by clusters and voids while shifting the density distribution toward higher densities, indicating delayed structure formation. Using minimum spanning tree (MST) analysis on galaxy-like objects, they demonstrate that approximately 70% of MST connections occur in filaments, making this method sensitive to neutrino mass and capable of distinguishing between effects of neutrinos and baryonic physics.
Why it matters
This research provides a novel statistical method for measuring neutrino mass through upcoming galaxy surveys like DESI, which could help resolve fundamental questions in particle physics and cosmology. The MST technique offers advantages over traditional two-point statistics for characterizing cosmic structure and could improve constraints on neutrino properties from observational data.
Understand the Science
arXiv:2512.16517v2 Announce Type: replace
Abstract: We explore the effects of massive neutrinos on the cosmic web using the FLAMINGO simulations. We classify the cosmic web into voids, sheets, filaments, and clusters, and find that massive neutrinos affect the environment by decreasing the volume occupied by clusters and voids. We find that increasing the neutrino mass shifts the volume-weighted density distribution towards higher densities and leads to a more narrow density distribution, which we interpret as neutrinos delaying structure formation. We construct the minimum spanning tree (MST) graph from the subhaloes, adopting a number density chosen to match that expected for DESI-like observations. We show that most MST edges lie in filaments, approximately 70% throughout different simulations, which we link to its sensitivity to neutrino mass. We also link the MST’s edge length signal at different scales to different cosmic web environments, with clusters dominating the signal at small scales, voids at longer scales, and filaments at intermediate scales. The strong correlation between MST edges and cosmic web environments reinforces the MST’s potential to be used as a classifier for large-scale structure in galaxy surveys. We compare the effects of baryonic physics and massive neutrinos and find that each produces distinct signatures in MST edge lengths. This analysis is performed in 3D space, using the true positions of subhaloes and not accounting for redshift space distortions. Nevertheless, these results emphasise the MST’s capability to go beyond two-point statistics, motivating future applications to real observational data.