The Arrowhead Mini-Supercluster of Galaxies

TL;DR

This paper identifies a new, small supercluster called the Arrowhead, using velocity shear tensor analysis and Wiener Filter reconstructions, revealing a distinct, cluster-free structure with specific size and mass.

Contribution

It introduces a novel kinematic method to define superclusters and identifies the Arrowhead Supercluster as a previously unrecognized structure.

Findings

The Arrowhead Supercluster is a small, cluster-free structure.

It has a characteristic size of approximately 25 Mpc.

Its mass is around 10^15 solar masses.

Abstract

Superclusters of galaxies can be defined kinematically from local evaluations of the velocity shear tensor. The location where the smallest eigenvalue of the shear is positive and maximal defines the center of a basin of attraction. Velocity and density fields are reconstructed with Wiener Filter techniques. Local velocities due to the density field in a restricted region can be separated from external tidal flows, permitting the identification of boundaries separating inward flows toward a basin of attraction and outward flows. This methodology was used to define the Laniakea Supercluster that includes the Milky Way. Large adjacent structures include Perseus-Pisces, Coma, Hercules, and Shapley but current kinematic data are insufficient to capture their full domains. However there is a small region trapped between Laniakea, Perseus-Pisces, and Coma that is close enough to be reliably characterized and that satisfies the kinematic definition of a supercluster. Because of its shape, it is given the name the Arrowhead Supercluster. This entity does not contain any major clusters. A characteristic dimension is ~25 Mpc and the contained mass is only ~10^15 Msun.