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The nebular spectra of the broad-lined, SN 1998bw-like Type Ic SN 2002ap arestudied by means of synthetic spectra. Two different modelling techniques areemployed. In one technique, the SN ejecta are treated as a single zone, whilein the other a density and abundance distribution in velocity is used from anexplosion model. In both cases, heating caused by gamma-ray and positrondeposition is computed (in the latter case using a Monte Carlo technique todescribe the propagation of gamma-rays and positrons), as is cooling viaforbidden-line emission. The results are compared, and although generalagreement is found, the stratified models are shown to reproduce the observedline profiles much more accurately than the single-zone model. The explosionproduced ~ 0.1 Msun of 56Ni. The distribution in velocity of the variouselements is in agreement with that obtained from the early-time models, whichindicated an ejected mass of ~ 2.5 Msun with a kinetic energy of 4 x 10^{51}erg. Nebular spectroscopy confirms that most of the ejected mass (~ 1.2 Msun)was oxygen. The presence of an oxygen-rich inner core, combined with that of56Ni at high velocities as deduced from early-time models, suggests that theexplosion was asymmetric, especially in the inner part.

The Aspherical Properties of the Energetic Type Ic SN 2002ap as Inferred from its Nebular Spectra