Galaxy interactions in filaments and sheets: effects of the large-scale structures versus the local density

TL;DR

This study investigates how large-scale cosmic structures like filaments and sheets influence galaxy interactions, star formation, and color changes, revealing environment-dependent differences up to 50 kpc separation.

Contribution

It provides new insights into the impact of large-scale structures on galaxy interactions, highlighting differences between filaments and sheets using SDSS data.

Findings

Higher star formation rates in filament pairs up to 50 kpc

Bluer galaxy colors in filaments compared to sheets at small separations

Reversal of trends at separations larger than 50 kpc

Abstract

The major interactions are known to trigger star formation in galaxies and alter their colour. We study the major interactions in filaments and sheets using the SDSS data to understand the influence of large-scale environments on the galaxy interactions. We identify the galaxies in filaments and sheets using the local dimension and also find the major pairs residing in these environments. The star formation rate and colour of the interacting galaxies as a function of pair separation are separately analyzed in filaments and sheets. The analysis is repeated for three volume limited samples covering different magnitude ranges. The major pairs residing in the filaments show a significantly higher star formation rate (SFR) and bluer colour than those residing in the sheets up to the projected pair separation of $\sim 50$ kpc. We observe a complete reversal of this behaviour for both the SFR and colour of the galaxy pairs having a projected separation larger than 50 kpc. Some earlier studies report that the galaxy pairs align with the filament axis. Such alignment inside filaments indicates anisotropic accretion that may cause these differences. We do not observe these trends in the brighter galaxy samples. The pairs in filaments and sheets from the brighter galaxy samples trace relatively denser regions in these environments. The absence of these trends in the brighter samples may be explained by the dominant effect of the local density over the effects of the large-scale environment.