Two Planes of Satellites in the Centaurus A Group

TL;DR

This study reveals that most galaxies in the Centaurus A Group are arranged in two thin, nearly parallel planes with specific dimensions and separation, providing insights into the group's large-scale structure.

Contribution

The paper identifies and characterizes two distinct, thin planes of satellite galaxies in the Centaurus A Group using precise distance measurements.

Findings

Most galaxies lie in two thin planes.

The planes are nearly parallel and slightly tilted.

The planes are separated by about 303 kpc.

Abstract

Tip of the red giant branch measurements based on Hubble Space Telescope and ground-based imaging have resulted in accurate distances to 29 galaxies in the nearby Centaurus A Group. All but two of the 29 galaxies lie in either of two thin planes roughly parallel with the supergalactic equator. The planes are only slightly tilted from the line-of-sight, leaving little ambiguity regarding the morphology of the structure. The planes have characteristic r.m.s. long axis dimensions of ~300 kpc and short axis dimensions of ~60 kpc, hence axial ratios ~0.2, and are separated in the short axis direction by 303 kpc.