2019MNRAS.482.4188S

Late-type disc galaxies are observed to have extended gas discs that are significantly larger than their optical discs. The Λ cold dark matter (ΛCDM) cosmological model predicts that luminous galaxies, such as the Milky-Way (MW), are hosts to a large number of low-mass dark matter sub-haloes (DMSHs), which are capable of interacting with the discs of galaxies. We aim to understand the kinematic impact of a DMSH collision with the extended gas disc of a galaxy. In order to study this, we use hydrodynamical simulations with a variety of parameters such as galaxy inclination, DMSH mass, and galaxy mass. To analyse the simulation results, we present two-dimensional (2D) kinematic and gas density maps of galaxies to investigate their unique features and structures. Along with this, we also implement a deep learning (DL) model to classify kinematic images of the simulated galaxies as either impacted (by the DMSH) or isolated. Through the use of these techniques, we have found that the impact of the DMSH causes features in both the 2D kinematic and gas density plots, most notably the development of a ∼1 kpc size H I hole in the gas-rich DMSH impact. Through the study of these maps, we identify certain features and the specific conditions required to induce them. The study of these features is important, as they can be observed with large upcoming H I surveys such as WALLABY and SKA.