Scenario I: Final snapshots of three models evolved from −2 Gyr until the current position of Leo T. We show two models that used the fiducial dwarf model D1, model M3 (S4M6) (left column) with a final tangential velocity of $u_{\mathrm{t}}=200\mathrm{km}{\mathrm{s}}^{-1}$ and model M4 (S4M7) (middle column) with $u_{\mathrm{t}}=300\mathrm{km}{\mathrm{s}}^{-1}$. We also show model M7 (S11M11) (right column), which uses the more massive dwarf model D2 and $u_{\mathrm{t}}=300\mathrm{km}{\mathrm{s}}^{-1}$. The first and second rows show the surface mass and line-of-sight (LOS) velocity maps projected according to attack angles θ_sky expected from the orbital orientation (Eq. (1)). We note that v_los are in the dark matter centre of mass rest frame. In the bottom row we include images with a projection of θ_sky = 90° to reveal the morphology and the maximum velocity gradients along the orbits. The centre of mass of the combined stellar and dark matter distributions is marked with white stars, and the gas peaks are marked with white crosses. To better represent the HI observations we made the calculations with gas colder than T < 10⁴ K. The v_los maps are in the rest frame of the dwarf’s dark matter centre of mass, and the centre of mass of the stellar and dark matter components overlap in all panels. The contours on the leading side may cover the velocity map due to the strong compression; this can be avoided by zooming in the pdf version. We note that ${\mathrm{\Sigma }}_{\mathrm{gas}}=1{\mathrm{M}}_{\odot }{\mathrm{pc}}^{-2}$ corresponds here to N_HI = 1.2 × 10²⁰ cm⁻², and the spacing between contours is $log\mathrm{\Sigma }/{\mathrm{M}}_{\odot }{\mathrm{pc}}^{-2}=0.2\mathrm{dex}$ for all simulation figures.