Hydrodynamical N-body simulations of the dwarf galaxies NGC 5474 and DDO 68
Raffaele Pascale (INAF - OAS Bologna)
Tuesday 02/03/2021 @ 14:00, Sala IV piano Battiferro
I will present hydrodynamical N-body numerical simulations aimed to reproduce the structural and kinematic properties of the peculiar local dwarf galaxies NGC 5474 and DDO 68. In case of NGC 5474, the possible origin of the compact round stellar structure, generally interpreted as the bulge of the galaxy, but unusually off-set by 1 kpc in projection from the visual and the kinematic centres of both the star and the gas discs, is investigated. By means of hydrodynamical N-body simulations I will show that it is very unlikely that the putative bulge of NGC 5474 is the bulge of the galaxy, since such a configuration would be hardly compatible with its smooth and regular spatial distribution. As an alternative scenario, I will present models where the putative bulge is an early-type satellite galaxy orbiting around NGC 5474, showing how the off-set can be easily reproduced by projection effects. In case of the local irregular dwarf galaxy DDO 68 I will present hydrodynamical N-body simulations that reproduce and explain its very irregular stellar structure and gas kinematics as the outcome of an ongoing merger with at least two smaller satellite galaxies. DDO 68 is an extremely metallicity deficient galaxy, with one of the lowest metallicity ever measured. Since one of the hypothesis invoked to explain extremely metal deficient galaxy is the dilution of the gas metallicity with primeval gas material recently accreted, I will present preliminary results based on simulations that show to what extent the ongoing merger can be called upon to explain the low metallicity of DDO 68.