Orateur
Alain BLANCHARD
(IRAP)
Description
We examine whether the MOND theory can reproduce the decline observed in the Milky Way’s rotation curve using Gaia data. MOND, which modifies Newtonian dynamics at very low accelerations (a₀ ≈ 1.2 × 10⁻¹⁰ m/s²), successfully explains the flat rotation curves of galaxies but struggles to account for this decline. A model based on a dark matter halo (NFW) with a scale radius of 4 kpc fits the decline well, whereas MOND fails with a standard baryonic model. By adjusting the parameters of the stellar and HI disk using an MCMC analysis, a good fit can be achieved, but this requires a very massive stellar disk (~10¹¹ M⊙) and a much lower value of a₀ than typically assumed, calling into question the effectiveness of MOND in this specific case.
