Dr. Elena Bannikova (INAF/OACN)
26 November 2025
11:30, Aula Piazzi
Abstract:
The Andromeda galaxy (M31) is characterized by an unusual double nucleus, revealed by HST. Its stellar nuclear disk shows a strong brightness asymmetry, usually attributed to stars lingering near the apocenters of eccentric orbits. However, the physical origin and long-term dynamics of this lopsided (m = 1) configuration remain unclear. Using N-body simulations, we show that a lopsided mode can arise spontaneously in a massive, geometrically thick stellar torus surrounding a supermassive black hole (SMBH). This mode produces a slowly precessing one-sided density enhancement, naturally generating an eccentric disk–like structure and causing a measurable offset of the SMBH from the barycenter of the system.