Tidal interactions at the edge of the Local Group: New evidence for tidal features in the Antlia Dwarf Galaxy

TL;DR

Deep imaging reveals tidal tails in the Antlia Dwarf Galaxy, indicating interactions with its neighbor NGC 3109, which influence its morphology despite its remote location at the edge of the Local Group.

Contribution

First detection of tidal features in the Antlia Dwarf Galaxy using deep imaging, highlighting environmental effects at the Local Group's edge.

Findings

Tidal tails are aligned with NGC 3109, suggesting gravitational interaction.

Antlia's morphology could be altered by multiple interactions with NGC 3109.

Environmental effects are significant even at the Local Group's boundary.

Abstract

Using deep B band imaging down to mu_{B} = 26 mag arcsec^{-2}, we present evidence for tidal tails in the Antlia Dwarf galaxy, one of the most distant members of the Local Group. This elongation is in the direction of Antlia's nearest neighbor, the Magellanic-type NGC 3109. The tail is offset by less than 10 degrees from a vector linking the centers of the two galaxies, indicative of interactions between the pair. Combined with the warped disc previously identified in NGC 3109, Antlia and NGC 3109 must be at a small separation for tidal features to be present in Antlia. We calculate that Antlia cannot be completely disrupted by NGC 3109 in a single interaction unless its orbit pericenter is less than 6 kpc, however multiple interactions could significantly alter its morphology. Therefore despite being located right at the edge of the Local Group, environmental effects are playing an important role in Antlia's evolution.