Radiative cooling-driven (thermal) instabilities in weakly magnetized, diffuse, hot plasmas

Astrophysical environments are diverse in characteristic density, temperature, and magnetic field. For example, intracluster and circumgalactic medium (ICM/CGM) are large-scale, mildly magnetized, weakly collisional, hot, and diffuse environments. On the other hand, solar and planetary coronae have strong magnetic fields in hot and relatively tighter gravitationally bound atmospheres. A common feature in many of these distinctly different environments is the multiphase nature of the medium, or in other words, the local coexistence of a range of temperatures and the lack of monolithic cold or hot phase. This feature suggests (i) maintenance of an approximate thermal equilibrium in a time-averaged sense and (ii) a mechanism to produce multiphase condensation despite an equilibrium. In this talk, I will discuss the physical mechanisms responsible for (i) and (ii) in the ICM/CGM using analytic models and numerical experiments. I will include a discussion on the permitted length scales in a multiphase medium. Further, I will highlight the role of the weak magnetic field in condensation (specifically, large-scale mode along the field) and maintenance of the hot background medium (energy transport problem). Some of these ideas can also be relevant to speculate on such instabilities and interpret solar prominence, clumpy AGN winds, and condensation in planetary coronae.