ANALYTICAL SOLUTIONS OF SPHERICALLY SYMMETRICAL COLLAPSE OF AN ANISOTROPIC FLUID BODY INTO A BLACK-HOLE

Einstein's field equations in a spherically symmetric case are investigated for an anisotropic fluid body. An equation of state T4 4=-k2T11 is imposed. On the boundary of the star, the junction conditions [Tab] nb=0 of Synge are required to be satisfied. In the interior of the fluid body the three strong energy inequalities of Hawking are required to hold. A class of analytical solutions, involving three parameters, are found which satisfy all the equations and the inequalities prior to the collapse of the boundary inside the event horizon. However, inside the black hole, the fluid undergoes a metamorphosis. It still remains an anisotropic fluid with positive energy density and "radial" pressure, but the fluid motion is superluminous or tachyonic. © 1995 American Institute of Physics.