# Peculiar Velocities of Galaxies Just Beyond the Local Group

## TL;DR

This study investigates the peculiar velocities of galaxies near the Local Group, revealing the expansion of the Local Void and the structure of nearby galaxies through precise distance measurements, enhancing understanding of local cosmic flows.

## Contribution

The paper provides new infrared observations of obscured galaxies, accurately measuring their distances and clarifying the local velocity field and structure of the nearby universe.

## Key findings

- Galaxies near the Local Group exhibit velocities indicating Local Void expansion.
- Four galaxies are confirmed to be part of a filamentary structure at ~7 Mpc.
- A nearby galaxy shows an anomalous velocity, suggesting complex local dynamics.

## Abstract

The Milky Way lies in a thin plane, the Local Sheet, a part of a wall bounding the Local Void lying toward the north supergalactic pole. Galaxies with accurate distances both above and below this supergalactic equatorial plane have systematically negative peculiar velocities. The interpretation of this situation is that the Local Void is expanding, giving members of the Local Sheet deviant velocities toward the south supergalactic pole. The few galaxies within the void are evacuating the void. Galaxies in a filament in the supergalactic south are not feeling the expansion so their apparent motion toward us is mainly a reflex of our motion. The model of the local velocity field was uncertain because the apex of our motion away from the Local Void lies in obscurity near the Galactic plane. Here, results of Hubble Space Telescope infrared observations are reported that find tip of the red giant branch distances to four obscured galaxies. All the distances are $\sim7$ Mpc, revealing that these galaxies are part of a continuous filamentary structure passing between the north and south Galactic hemispheres and sharing the same kinematic signature of peculiar velocities toward us. A fifth galaxy nearby in projection, GALFA-DW4, has an ambiguous distance. If nearby at $\sim 3$ Mpc, this galaxy has an anomalous velocity away from us of +348 km/s. Alternatively, perhaps the resolved stars are on the asymptotic giant branch and the galaxy is beyond 6 Mpc whence the observed velocity would not be unusual.