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

Abstract

Giant Low Surface Brightness galaxies (gLSBGs), such as Malin 1, host extended stellar and gaseous discs exceeding $100\mathrm{kpc}$ in radius. Their formation and evolution remain debated, with satellite interactions and accretion streams proposed as key drivers. Malin 1 exhibits multiple companions and two giant stellar streams extending up to $200\mathrm{kpc}$. We investigate the orbital dynamics of Malin 1's satellites and their potential connection to these streams. Using optical and HI rotation curve data, we constructed gravitational potentials for Malin 1 incorporating stellar, gaseous, and dark matter components under both Navarro-Frenk-White (NFW) and pseudo-isothermal (ISO) halo profiles. Several scenarios yield bound orbital solutions. The ISO model ($M_{\mathrm{virial}}\approx 2.6\times 10^{12}{M}_{\odot }$) favours bound satellite orbits more than the lower-mass NFW model ($M_{\mathrm{virial}}\approx 1.4\times 10^{12}{M}_{\odot }$). The giant stellar streams could be substructures located along the leading and trailing trajectories of satellite companions. Orbital modeling indicates that the distant satellite eM1 reached pericentre $\sim 1.6\mathrm{Gyr}$ ago, whereas closer companions interacted as recently as $\sim 100\mathrm{Myr}$ ago, with one companion currently experiencing strong interaction. Another close companion displays leading/trailing arms in a radial orbit, alongside a polar orbit solution. Unbound solutions linking satellites with streams are also identified. These alignments suggest past interactions shaped Malin 1's morphology, providing new constraints on gLSBG dynamical evolution consistent with recent kinematic studies.

20 pages, 8 figures. Accepted for publication in A&A