Thermal instabilities in cooling flows: The evolution of nearly spherical perturbations
Abstract
The temporal evolution of thermally unstable blobs in connection with the problem of mass accretion in cooling flows is studied numerically, in one and two dimensions. The hydrodynamic equations are solved in spherical geometry for an initially homogeneous cooling medium, including thermal conduction. The initial isobaric perturbations are followed in time until self gravity effects, not included in the equations, are thought to become important. In the one dimensional case, it is found that after the linear phase the perturbation evolves on time scales much shorter than the linear ones and depending on the initial matter density, a cool, dense core of size approximately 0.001  0.01 times the initial perturbation scale size forms. This grows in size due to continuous accretion from the (hotter) outside gas and may become eventually gravitationally unstable. The one dimensional results are compared with others obtained for a planeparallel slab geometry. The qualitative difference between a one dimensional and a two dimensional calculation with otherwise very similar physical parameters is shown.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 February 1990
 Bibcode:
 1990STIN...9119365B
 Keywords:

 Cooling Flows (Astrophysics);
 Evolution (Development);
 Galactic Clusters;
 Perturbation;
 Thermal Instability;
 Accretion Disks;
 Hydrodynamic Equations;
 Hydrodynamics;
 Numerical Analysis;
 Temperature;
 Fluid Mechanics and Heat Transfer