The NGC 1023 Galaxy Group: An Anti-Hubble Flow?

TL;DR

This paper examines the structure and dynamics of the NGC 1023 galaxy group, revealing a virialized core and an infalling outer component, contrasting with the Local Group's receding dwarf galaxies, and discusses implications of dark energy.

Contribution

It provides new insights into the structure of the NGC 1023 group, highlighting the dominance of self-gravity and the potential influence of dark energy on galaxy flows.

Findings

NGC 1023 has a virialized core and infalling outer component.

The Local Group's outer dwarfs form a receding Hubble flow.

Dark energy may influence galaxy flow dynamics at 1.4-3 Mpc.

Abstract

We discuss recently published data indicating that the nearby galaxy group NGC 1023 includes an inner virialized quasi-stationary component and an outer component comprising a flow of dwarf galaxies falling toward the center of the system. The inner component is similar to the Local Group of galaxies, but the Local Group is surrounded by a receding set of dwarf galaxies forming the very local Hubble flow, rather than a system of approaching dwarfs. This clear difference in the structures of these two systems, which are very similar in other respects, may be associated with the dark energy in which they are both imbedded. Self-gravity dominates in the Local Group, while the anti-gravity produced by the cosmic dark-energy background dominates in the surrounding Hubble flow. In contrast, self-gravity likewise dominates throughout the NGC 1023 Group, both in its central component and in the surrounding Santi-Hubble flow. The NGC 1023 group as a whole is apparently in an ongoing state of formation and virialization. We may expect that there exists a receding flow similar to the local Hubble flow at distances of 1.4-3 Mpc from the center of the group, where anti-gravity should become stronger than the gravity of the system.