Analyzing the cosmic web environment in the vicinity of grand-design and flocculent spirals with local geometric index

TL;DR

This study introduces a new local geometric index to classify galaxy environments and finds that grand-design spirals predominantly reside in dense regions, while flocculent spirals are more common in sparse environments, with statistically significant results.

Contribution

The paper presents a novel local geometric index for environmental classification and applies it to distinguish the environments of different spiral galaxy types.

Findings

Grand-design spirals mainly in clusters and filaments (~78%)

Flocculent spirals more common in voids and sheets (>10%)

Results are statistically significant with p-value < 10^-3

Abstract

We explore the environment of a combined set of $367$ grand-design and $619$ flocculent spiral galaxies. We introduce a novel estimator called the \textit{local geometric index} to quantify the morphology of the local environment of these $986$ spirals. The local geometric index allows us to classify the environment of galaxies into voids, sheets, filaments, and clusters. We find that grand-designs are mostly located in dense environments like clusters and filaments ($\sim 78\%$), whereas the fraction of the flocculents lying in sparse environments like voids and sheets is significantly higher ($ > 10\%$) than that of the grand-designs. A $p$-value $<$ $10 ^{-3}$ from a Kolmogorov-Smirnov test indicates that our results are statistically significant at $99.9\%$ confidence level. Further, we note that dense environments with large tidal flows are dominated by the grand-designs. On the other hand, low-density environments such as sheets and voids favor the growth of flocculents.