Effects of causality on the fluidity and viscous horizon of quark-gluon plasma

The second order Israel-Stewart-M$\ddot{u}$ller relativistic hydrodynamics has been applied to study the effects of causality on the acoustic oscillation in relativistic fluid. Causal dispersion relations have been derived with non-vanishing shear viscosity, bulk viscosity and thermal conductivity at non-zero temperature and chemical potential. These relations have been used to investigate the fluidity of Quark Gluon Plasma (QGP) at finite temperature ($T$). Results of the first order dissipative hydrodynamics have been obtained as limiting case of the second order theory. The effects of the causality on the fluidity near the transition point and on viscous horizon are found to be significant. We observe that the inclusion of causality reduces the fluidity of QGP. It has also been shown that the inclusion of large magnetic field in the causal hydrodynamics alters the fluidity of QGP