The maximum extent of the filaments and sheets in the cosmic web: an analysis of the SDSS DR17

TL;DR

This study estimates the maximum size of filaments and sheets in the cosmic web using SDSS data, finding they can extend up to approximately 130 Mpc, with potential for larger scales in future surveys.

Contribution

It introduces a novel shuffling method to statistically determine the maximum extent of cosmic filaments and sheets in three dimensions.

Findings

Filaments and sheets can extend up to about 130 Mpc.

Shuffling reduces filamentarity and planarity at scales below this size.

The method can be applied to larger surveys for more accurate measurements.

Abstract

Filaments and sheets are striking visual patterns in cosmic web. The maximum extent of these large-scale structures are difficult to determine due to their structural variety and complexity. We construct a volume-limited sample of galaxies in a cubic region from the SDSS, divide it into smaller subcubes and shuffle them around. We quantify the average filamentarity and planarity in the three-dimensional galaxy distribution as a function of the density threshold and compare them with those from the shuffled realizations of the original data. The analysis is repeated for different shuffling lengths by varying the size of the subcubes. The average filamentarity and planarity in the shuffled data show a significant reduction when the shuffling scales are smaller than the maximum size of the genuine filaments and sheets. We observe a statistically significant reduction in these statistical measures even at a shuffling scale of $\sim 130 \,$Mpc, indicating that the filaments and sheets in three dimensions can extend up to this length scale. They may extend to somewhat larger length scales that are missed by our analysis due to the limited size of the SDSS data cube. We expect to determine these length scales by applying this method to deeper and larger surveys in future.