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Full-Text Articles in Physical Sciences and Mathematics
Non-Isobaric Thermal Instability, Tim Waters, Daniel Proga
Non-Isobaric Thermal Instability, Tim Waters, Daniel Proga
Physics & Astronomy Faculty Research
Multiphase media have very complex structure and evolution. Accurate numerical simulations are necessary to make advances in our understanding of this rich physics. Because simulations can capture both the linear and nonlinear evolution of perturbations with a relatively wide range of sizes, it is important to thoroughly understand the stability of condensation and acoustic modes between the two extreme wavelength limits of isobaric and isochoric instability as identified by Field. Partially motivated by a recent suggestion that large non-isobaric clouds can "shatter" into tiny cloudlets, we revisit the linear theory to survey all possible regimes of thermal instability. We uncover …
Cloud Coalescence: A Dynamical Instability Affecting Multiphase Environments, Tim Waters, Daniel Proga
Cloud Coalescence: A Dynamical Instability Affecting Multiphase Environments, Tim Waters, Daniel Proga
Physics & Astronomy Faculty Research
Mass and size distributions are the key characteristics of any astrophysical object, including the densest clumps comprising the cold phase of multiphase environments. In our recent papers, we showed how individual clouds of various sizes form and evolve in active galactic nuclei. In particular, we showed that large clouds undergo damped oscillations as a response to their formation process. Here we follow up this investigation, addressing how different size clouds interact. We find that smaller clouds become trapped in the advective flows generated by larger clouds. The explanation for this behavior leads to a rather remarkable conclusion: even in the …