# The Extended Local Supercluster

**Authors:** P. J. E. Peebles  
**arXiv:** [2112.12847](https://arxiv.org/abs/2112.12847)  
**Date:** 2021-12-23  
**Summary page:** https://www.summarizepaper.com/en/paper/2112.12847v3/

## Key points

- The extended Local Supercluster is a region at least 170 Mpc across.
- Different types of galaxies show varying degrees of alignment with the plane of the de Vaucouleurs Local Supercluster.
- Clusters of galaxies and radio galaxies at redshifts less than 0.02 are concentrated at low supergalactic latitudes, while the most luminous early-type galaxies are also concentrated in this region.
- Similarly luminous spirals do not appear to be noticeably aligned with this plane.
- The most luminous galaxies in the infrared, LIRGs, show little correlation with this plane.
- Spirals as bright as the most luminous ellipticals at 2.2 𝜇 do not appear to be concentrated on this plane either.
- Mean density at a distance of 0.5 Mpc from an LIRG is comparable to mean density from a cluster of galaxies; however, mean density 5 Mpc from an LIRG is well below mean density from a cluster and only slightly greater than cosmic mean density.
- Observations raise questions about how these structures form and evolve over time and offer insights into large-scale structure formation processes in our universe.

## Summary

The extended Local Supercluster is a region at least 170 Mpc across where different types of galaxies show varying degrees of alignment with the plane of the de Vaucouleurs Local Supercluster. Clusters of galaxies and radio galaxies at redshifts less than 0.02 are concentrated at low supergalactic latitudes, while the most luminous early-type galaxies are also concentrated in this region. However, similarly luminous spirals do not appear to be noticeably aligned with this plane. The most luminous galaxies in the infrared, LIRGs, show little correlation with this plane. It is noted that since clusters of galaxies, radio galaxies and most luminous early-type galaxies all prefer dense regions, their samples are related but differ in how they reveal large-scale structure. Spirals as bright as the most luminous ellipticals at 2.2 𝜇 do not appear to be concentrated on this plane either. The mean density at a distance of 0.5 Mpc from an LIRG is comparable to the mean density at that distance from a cluster of galaxies; however, the mean density 5 Mpc from an LIRG is well below the mean density at that distance from a cluster and only slightly greater than the cosmic mean density. In conclusion, it has been established that we are in a region where different types of galaxies exhibit varying degrees of alignment with the Local Supercluster's plane. While some types show strong correlation with this structure, others do not appear to align significantly with it. These observations raise questions about how these structures form and evolve over time and offer insights into large-scale structure formation processes in our universe.