The VIMOS Public Extragalactic Redshift Survey (VIPERS): Galaxy segregation inside filaments at $z \simeq 0.7$

TL;DR

This study detects and analyzes the distribution of galaxies within cosmic filaments at redshift 0.7, revealing mass and activity-based segregation patterns that inform galaxy formation theories.

Contribution

First quantitative detection of filamentary structures at z ≈ 0.7 in a large survey, showing galaxy segregation based on mass and activity within filaments.

Findings

Massive and quiescent galaxies are closer to filament axes.

Low-mass star-forming galaxies are found at filament edges.

Results support theories of galaxy assembly via mergers and cosmic flows.

Abstract

We present the first quantitative detection of large-scale filamentary structure at $z \simeq 0.7$ in the large cosmological volume probed by the VIMOS Public Extragalactic Redshift Survey (VIPERS). We use simulations to show the capability of VIPERS to recover robust topological features in the galaxy distribution, in particular the filamentary network. We then investigate how galaxies with different stellar masses and stellar activities are distributed around the filaments and find a significant segregation, with the most massive or quiescent galaxies being closer to the filament axis than less massive or active galaxies. The signal persists even after down-weighting the contribution of peak regions. Our results suggest that massive and quiescent galaxies assemble their stellar mass through successive mergers during their migration along filaments towards the nodes of the cosmic web. On the other hand, low-mass star-forming galaxies prefer the outer edge of filaments, a vorticity rich region dominated by smooth accretion, as predicted by the recent spin alignment theory. This emphasizes the role of large scale cosmic flows in shaping galaxy properties.