A disk and no signatures of tidal distortion in the galaxy "lacking" dark matter NGC 1052-DF2

TL;DR

Deep imaging of NGC 1052-DF2 reveals no tidal features, suggesting it has a low-inclination disk and a higher dark matter content than previously thought, aligning it with typical galaxies of similar stellar mass.

Contribution

This study provides the deepest imaging analysis of NGC 1052-DF2, challenging prior claims of its dark matter deficiency by revealing a disk structure and higher dark matter content.

Findings

No evidence of tidal tails or stripping.

Galaxy exhibits a low-inclination disk structure.

Dark matter content is consistent with similar stellar mass galaxies.

Abstract

Using ultra-deep imaging ($\mu_g = 30.4$ mag/arcsec$^2$; 3$\sigma$, 10"x10"), we probed the surroundings of the first galaxy "lacking" dark matter KKS2000[04] (NGC 1052-DF2). Signs of tidal stripping in this galaxy would explain its claimed low content of dark matter. However, we find no evidence of tidal tails. In fact, the galaxy remains undisturbed down to a radial distance of 80 arcsec. This radial distance triples previous spatial explorations of the stellar distribution of this galaxy. In addition, the distribution of its globular clusters (GCs) is not extended in relation to the bulk of the galaxy (the radius containing half of the GCs is 21 arcsec). We also found that the surface brightness radial profiles of this galaxy in the g and r bands decline exponentially from 35 to 80 arcsec. That, together with a constant ellipticity and position angle in the outer parts of the galaxy strongly suggests the presence of a low-inclination disk. This is consistent with the evidence of rotation found for this object. This finding implies that the dynamical mass of this galaxy is a factor of 2 higher than previously reported, bringing the dark matter content of this galaxy in line with galaxies of similar stellar mass.