In this paper, we examine the issue of characterizing the transport associated with gravitational instabilities in relatively cold discs, discussing in particular the conditions under which it can be described within a local, viscous framework. We present the results of global, three-dimensional, smoothed particle hydrodynamics simulations of self-gravitating accretion discs, in which the disc is cooled using a simple parametrization for the cooling function. Our simulations show that the disc settles in a 'self-regulated' state, where the axisymmetric stability parameter Qapproximate to 1 and where transport and energy dissipation are dominated by self-gravity. We have computed the gravitational stress tensor and compared our results with expectations based on a local theory of transport. We find that, as long as the disc mass is smaller than 0.25M(star) and the aspect ratio H/Rless than or similar to 0.1, transport is determined locally, thus allowing for a viscous treatment of the disc evolution.
|Titolo:||Testing the locality of transport in self-gravitating accretion discs|
LODATO, GIUSEPPE (Primo)
|Parole Chiave:||accretion, accretion discs; gravitation; instabilities; stars : formation; galaxies : active|
|Settore Scientifico Disciplinare:||Settore FIS/05 - Astronomia e Astrofisica|
|Data di pubblicazione:||2004|
|Digital Object Identifier (DOI):||10.1111/j.1365-2966.2004.07811.x|
|Appare nelle tipologie:||01 - Articolo su periodico|