Cosmology and neutrino mass with the Minimum Spanning Tree

TL;DR

This paper demonstrates that the minimum spanning tree (MST) captures higher-order cosmic web information, providing tighter constraints on neutrino mass and cosmological parameters than the power spectrum alone, especially when combined.

Contribution

It introduces the use of MST in cosmology for neutrino mass estimation, showing its advantages over traditional power spectrum analysis and its potential for future surveys.

Findings

MST yields tighter constraints on neutrino mass and certain cosmological parameters.

Combining MST with power spectrum improves parameter constraints by a factor of two or more.

MST's sensitivity to small-scale clustering enhances neutrino mass detection.

Abstract

The information content of the minimum spanning tree (MST), used to capture higher-order statistics and information from the cosmic web, is compared to that of the power spectrum for a $\nu\Lambda$CDM model. The measurements are made in redshift space using haloes from the Quijote simulation of mass $\geq 3.2\times 10^{13}\,h^{-1}{\rm M}_{\odot}$ in a box of length $L_{\rm box}=1\,h^{-1}{\rm Gpc}$. The power spectrum multipoles (monopole and quadrupole) are computed for Fourier modes in the range $0.006 < k < 0.5\, h{\rm Mpc}^{-1}$. For comparison the MST is measured with a minimum length scale of $l_{\min}\simeq13\,h^{-1}{\rm Mpc}$. Combining the MST and power spectrum allows for many of the individual degeneracies to be broken; on its own the MST provides tighter constraints on the sum of neutrino masses $M_{\nu}$ and cosmological parameters $h$, $n_{\rm s}$, and $\Omega_{\rm b}$ but the power spectrum alone provides tighter constraints on $\Omega_{\rm m}$ and $\sigma_{8}$. Combined we find constraints that are a factor of two (or greater) on all parameters with respect to the power spectrum (for $M_{\nu}$ there is a factor of four improvement). These improvements appear to be driven by the MST's sensitivity to small scale clustering, where the effect of neutrino free-streaming becomes relevant, and high-order statistical information in the cosmic web. The MST is shown to be a powerful tool for cosmology and neutrino mass studies, and therefore could play a pivotal role in ongoing and future galaxy redshift surveys (such as DES, DESI, \emph{Euclid}, and Rubin-LSST).