HIGH-POWERED GRAVITATIONAL NEWS

We describe the computation of the Bondi news for gravitational radiat ion. We have implemented a computer code for this problem. We discuss the theory behind it as well as the results of validation tests. Our a pproach uses the compactified null cone formalism, with the computatio nal domain extending to future null infinity and with a world tube as inner boundary. We calculate the appropriate;ll Einstein equations in computational eth form in (a) the interior of the computational domain and (b) on the inner boundary. At future null infinity, we transform the computed data into standard Bondi coordinates and sa an able to ex press the news in terms of its standard N+ and h(x), polarization comp onents. The resulting code is stable and second-order convergent. It r uns successfully even in the highly nonlinear case, and has been teste d with the news as high as 400, which represents a gravitational radia tion power of about 10(13)M./sec. [S0556-2821(97)03022-1].