The galaxy "missing dark matter" NGC1052-DF4 is undergoing tidal disruption

TL;DR

Deep optical imaging reveals tidal tails in NGC1052-DF4, indicating ongoing tidal disruption that explains its low dark matter content and aligns with current galaxy formation models.

Contribution

This study provides direct evidence of tidal disruption in NGC1052-DF4, explaining its lack of dark matter through interaction-induced stripping.

Findings

Tidal tails detected in NGC1052-DF4.

Less than 1% of dark matter remains in the galaxy.

Stars are only beginning to be affected by tidal interaction.

Abstract

The existence of long-lived galaxies lacking dark matter represents a challenge to our understanding of how galaxies form. Here, we present evidence that explains the lack of dark matter in one of such galaxies: NGC1052-DF4. Deep optical imaging of the system has detected tidal tails in this object caused by its interaction with its neighbouring galaxy NGC1035. As stars are more centrally concentrated than the dark matter, the tidal stripping will remove a significant percentage of the dark matter before affecting the stars of the galaxy. Only ~7% of the stellar mass of the galaxy is in the tidal tails, suggesting that the stars of NGC1052-DF4 are starting only now to be affected by the interaction, while the percentage of remaining dark matter is <1%. This naturally explains the low content of dark matter inferred for this galaxy and reconciles these type of galaxies with our current models of galaxy formation.