Stiffness effects on the dynamics of bar-mode instability in full General Relativity

We present results on the effect of the stiffness of the equation of state on dynamical bar-mode instability in rapidly rotating polytropic models of neutron stars in full General Relativity. We determine the change on the threshold for the emergence of the instability when the adiabatic $\Gamma$ index is changed from 2 to 2.75 to mimic the behavior of realistic equation of state. We also extend the analysis to low value of the instability parameter $\beta$ to check for the presence of low-$\beta$ or shearing instabilities.