Exploring the stellar streams and satellites around the giant low surface brightness galaxy Malin 1

TL;DR

This study models the orbital dynamics of satellites around Malin 1, a giant low surface brightness galaxy, revealing how past interactions with satellites and streams have influenced its morphology and evolution.

Contribution

It introduces detailed gravitational models and explores formation scenarios, highlighting the role of satellite interactions and different halo profiles in shaping Malin 1.

Findings

ISO halo model favors bound satellite orbits more than NFW.

Giant stellar streams may be substructures of satellites.

Some satellites interacted as recently as 100 Myr ago.

Abstract

Context. Giant Low Surface Brightness galaxies, such as Malin 1, host extended discs exceeding 100 kpc. Their formation and evolution remain debated, with interactions with satellite galaxies and accretion streams proposed as key contributors. Malin 1 hosts satellites and exhibits two giant stellar streams, likely the result of past interactions. Aims. We investigate the orbital dynamics of Malin 1's satellites and their possible connections with observed stellar streams, testing their nature with different formation scenarios. Methods. We constructed gravitational potentials using optical and HI data, including stellar, gaseous, and dark matter components, and explored a wide parameter space while testing NFW and ISO halo profiles. Results. Some scenarios produced bound solutions. The ISO halo model ($M_{\text{Virial}} \approx 2.6 \times 10^{12}~M_{\odot}$) favours bound satellite orbits more than the NFW model ($M_{\text{Virial}} \approx 1.4 \times 10^{12}~M_{\odot}$). Giant stellar streams could be substructures of some satellite galaxies along their leading and trailing trajectories. The most distant Malin 1 satellite could have reached pericenter $\sim 1.6$ Gyr ago, while closer companions interacted as early as $\sim 100$ Myr ago. At the same time, one close companion displays both leading and trailing arms in radial and polar orbits. Furthermore, we also identify some unbound solutions linking satellites with streams. Conclusions. Satellites and stream alignment indicate that past interactions shaped Malin 1's morphology. Our modelling constrains progenitors and orbital histories, providing insights into the dynamical evolution of gLSBGs. Findings are consistent with recent studies using Malin 1 kinematic data.