Speaker
Description
It has been shown that the dynamics of the Milky Way satellites is determined not only by the MW but also significantly affected by the LMC. Recently, it has been demonstrated that the Tucana IV dwarf had a close passage (~4 kpc) with the LMC ~130 Myr ago. I will start this talk by describing the results of the orbit rewinding of the MW dwarfs, showing that Tucana IV was likely strongly distorted by the LMC’s tides. Then, I will present the results of N-body simulations of this encounter run with Gadget-3 and a recently developed restricted N-body tool, which is much faster than classical N-body. It uses the low-order multipole expansion of the effective particle potential to compute the forces instead of considering forces from individual particles. To study the effect of the LMC on Tucana IV, I run multiple simulations sampling over the uncertainties in Tucana IV’s and the LMC’s phase space coordinates and the LMC’s mass. In many of these simulations, the orientations of the outskirts of Tucana IV match the observed orientation. However, the inner region of Tucana IV remains spherical, in contrast to its observed ellipticity. I will also present the results of simulations for Tucana IV initialized with an aspherical shape, i.e. a triaxial dark matter halo and stellar distribution, and compare these with observations. Looking forward, this collision between Tucana IV and the LMC, in addition to the LMC’s effect on stellar streams, will help further understand the past orbit of the LMC.
