Perturbation Effects and the Evolution of gLSBGs: The Case of Malin 1 - Past & Future Interactions with Satellite Galaxies

We study the environment of the giant low surface brightness galaxy Malin 1 analysing the orbital history of its satellite galaxies by exploring possible close encounters in the past. We find orbits with trajectories that can connect the location of the satellite exo-Malin 1 with an observed stellar stream candidate, which could indicate that Malin 1 had a satellite interaction ∼ 3Gyr ago.

Low surface brightness galaxies (LSBGs) dominate the volume density of galaxies in the universe. Moreover, giant LSBGs (gLSBGs) have extended stellar and gaseous disks, with Malin 1 being an impressive example given its 200 kpc diameter disk with giant spiral arms, low star formation, and flat rotation curve, suggesting a massive dark matter halo. Its environment shows several possible interacting objects (Reshetnikov et al. 2010): a satellite galaxy candidate exo-Malin 1 located at 358 kpc north east from the centre of Malin 1, and a giant stellar stream candidate extending from Malin 1 centre in direction to exo-Malin 1 (Galaz et al. 2015). In this project, we explore the hypothesis that the stellar stream is related to exo-Malin 1. For this, we search satellite orbits that match the location of the satellite and overlay with the the visible stellar stream (g and r bands).

We model optical and HI rotation curve data to obtain gravitational potentials of Malin 1 (stellar, gaseous, dark matter components), finding a total virial mass and radius of ∼ 1.8 ×10¹² M_⊙ and ∼ 251 kpc. Using this potentials we perform the orbital modelling of the satellite galaxy exo-Malin 1 with DELOREAN (Blaña et al. 2020) exploring the parameter space with a Monte Carlo technique using emcee (Foreman-Mackey et al. 2013). In addition, forward orbits are explored.

We present an orbital solution that connects Malin 1, the stellar stream, and exo-Malin 1, assuming that the latter is at a Line-of-Sight (LoS) distance of Z = −100 kpc from Malin 1, showing a maximum LoS velocity difference along the orbit of ∼ 300km/s. This model predicts that the stream could be material trailing exo-Malin 1 and that future kinematic measurements on the stream could constrain their orbital history. Additionally, further orbital and N-body simu- lation analysis could reveal the interaction history of Malin 1 and its extended disk while comparing with galaxy evolution models (Bustos-Espinoza et al. in prep.).