0 A pr 1 99 8 GRAVITATIONAL CAPTURE AND SCATTERING OF STRAIGHT TEST STRINGS WITH LARGE IMPACT PARAMETERS ∗

The capture or scattering of an initially straight infinite test cosmic string by a Kerr-Newman black hole, or by any other small source of an electrovac gravitational field, is analyzed analytically when the string moves with initial velocity v 0 and large impact parameter z 0 = b ≫ M so that the string stays very nearly straight (except during the final capture process, if that occurs, or except far behind the gravitating object, if b ≫ M/ 1 − v 2 0). The critical impact parameter for capture at low velocities, v 0 ≪ 1 − Q 2 /M 2 , is shown to be b crit = (π/2)(M 2 − Q 2)/v 0 + O(M). For all b > b crit , the displacement of the string from the plane of the gravitating object after the scattering approaches the final value z f ≈ b 2 − (π/2)(M 2 − Q 2)/v 0 −2πM v 0 / 1 − v 2 0 , for any v 0 , so long as b ≫ M .