Halo Spin Depends on The Distance to Cosmic Filament

TL;DR

This study uses observational data to find a subtle but significant correlation between dark matter halo spin and proximity to cosmic filaments, implying filamentary tidal forces influence halo spin.

Contribution

First observational evidence showing a correlation between halo spin and filament distance, highlighting the impact of cosmic filaments on galaxy properties.

Findings

Halo spin is higher closer to filaments.

A statistically significant correlation was observed.

Tidal forces from filaments may influence halo spin.

Abstract

We employ a semi-analytical methodology to estimate the dark matter halo spin of HI-rich galaxies in the Arecibo Legacy Fast Alfa Survey and investigate the relationship between halo spin and the proximity of galaxies to cosmic filaments. We exclude galaxies with low HI signal-to-noise ratios, those potentially influenced by velocity dispersions, and those affiliated with galaxy clusters/groups. Additionally, we apply a mass-weighting technique to ensure consistent mass distribution across galaxy samples at varying distances from filaments. Our analysis reveals, for the first time, a subtle yet statistically significant correlation between halo spin and filament distance in observational data, indicating higher spins closer to filaments. This suggests that the tidal forces exerted by filaments may impact the spin of dark matter halos.