Cooling driven coagulation

Understand

Astrophysical gases such as the interstellar-, circumgalactic- or intracluster-medium are commonly multiphase, which poses the question of the structure of these systems.

• While there are many known processes leading to fragmentation of cold gas embedded in a (turbulent) hot medium, in this work, we focus on the reverse process: coagulation.
• This is often seen in wind-tunnel and shearing layer simulations, where cold gas fragments spontaneously coalesce.
• Using 2D and 3D hydrodynamical simulations, we find that sufficiently large ($\gg c_{\rm s} t_{\rm cool}$), perturbed cold gas clouds develop pulsations which ensure cold gas mass growth over an extended period of time ($\gg r / c_{\rm s}$).