Beyond the surface: hydrodynamical N-body simulations of the interacting dwarf galaxies NGC 5238 and UGC 8760

TL;DR

This paper uses hydrodynamical N-body simulations to explain faint tidal features around two dwarf galaxies as interactions with smaller satellite systems, supporting cosmological models of galaxy formation.

Contribution

It presents detailed simulations that link observed low-surface brightness features to recent interactions with small satellites, consistent with ΛCDM cosmology.

Findings

Tidal features are caused by interactions with satellites of a few 10^5 M_7, 50 times less massive.

Simulations match observed asymmetries and substructures in the dwarf galaxies.

Satellite-to-host mass ratio is approximately 1:10, aligning with cosmological predictions.

Abstract

From deep imaging data obtained with the Large Binocular Telescope as part of the Smallest Scale of Hierarchy Survey (SSH), we have discovered low-surface brightness tidal features around NGC 5238 and UGC 8760, two nearby and relatively isolated dwarf galaxies with stellar masses of approximately $10^8 M_\odot$ and $2\times10^7 M_\odot$, respectively. In this study, we present detailed hydrodynamical $N$-body simulations that explain the observed faint substructures as the outcome of interactions between the dwarf galaxies and smaller satellite systems. We show that the asymmetric stellar distribution of NGC 5238 and the low-luminosity substructures observed to the northeast of UGC 8760 can be well attributed to recent interactions with smaller galaxies, each with a stellar mass roughly a few $10^5 M_\odot$, 50 times less massive than their respective hosts. In the simulations, these satellites have stellar and dark-matter masses consistent with the ones predicted by $\Lambda$CDM cosmology and share properties similar to those of local dwarf galaxies with similar stellar masses. The satellite-to-main galaxy mass ratio is approximately 1:10 in both cases. This satellite population aligns closely with predictions from cosmological simulations in terms of the number and mass relative to the host galaxy mass.