Abstract Details
| Name: Prakriti Pal Choudhury Affiliation: Indian Institute of Science, Bangalore Conference ID: ASI2015_677 Title : Numerical global eigenmode analysis of thermal instability in the intracluster medium Authors and Co-Authors : Prateek Sharma Indian Institute of Science, Bangalore Abstract Type : Poster Abstract Category : Extragalactic astronomy Abstract : Numerical simulations of thermal instability in hydrostatic and thermal equilibrium have shown that the local thermal instability leads to multiphase gas if the background cooling time is sufficiently short. Cartesian, plane-parallel simulations show that cold gas condenses out of the hot phase, starting from small perturbations, if the ratio of the local cooling time to the local free-fall time (tcool /tff ) is less than 1. The same setup in spherical geometry, and with background profiles similar to cluster cores, shows that cold gas condenses if this critical ratio is less than 10; i.e., it is much easier for cold gas to condense out in a spherical system. This tcool /tff ∼ 10 threshold explains the tight correlation between the presence of extended cold (104 K) gas and the core entropy of the X-ray gas (107 K). We perform a numerical global eigenmode analysis of thermal instability in spherical and Cartesian geometries in order to understand this important geometrical effect. |