Effects of entropy distributions on non-axisymmetric unstable modes in differentially rotating tori and cylinders

Effects of entropy distributions on non-axisymmetric unstable modes in differentially rotating objects are examined. The entropy distributions are given to satisfy the stability criterion for local perturbations. We examine how the entropy gradients modify the global unstable modes, by solving linear perturbation equations for various cylinders and tori with entropy gradients. It is found that the entropy distributions do not violently change the unstable modes, but affect the nature of the waves outside the corotation point. As the result, the entropy gradients change the growth rates, but do not always reduce them. (author)