Heating of galactic discs by infalling satellites

摘要: We develop an analytic model to calculate the rate at which galaxy discs are heated by dark matter substructures orbiting in their haloes. The takes into account internal structure, mass function and accretion of satellites expected ΛCDM cosmology, as well growth disc mergers, but it ignores resonant heating dynamical effects spiral arms bars. calibrate this against N-body simulations demonstrate that is able reproduce rates within a factor 3 majority cases. Our gives distribution scaleheights for galaxies different luminosities. For L* galaxies, predicts median thickness only 5 per cent radial scalelength if substructure source heating. increases nearly 20 when due gravitational scattering stars molecular clouds also included. latter value close estimated observationally Milky Way galaxy. predicted consistent with recent observational determination sub-L* Bizyaev & Mitronova. Thus, observed stellar seems be entirely compatible abundance haloes standard Λ-dominated cold structure formation. In Ω0= 1 universe, our best formation produces similar scaleheights, consequence fact amounts accreted during lifetime 0.3, Λ0= 0.7 cosmologies.