The aspherical properties of the energetic type Ic SN 2002ap as inferred from its nebular spectra

P. A. Mazzali, K. S. Kawabata, K. Maeda, R. J. Foley, K. Nomoto, J. Deng, T. Suzuki, M. Iye, N. Kashikawa, Y. Ohyama, A. V. Filippenko, Y. Qiu, J. Wei

Research output: Contribution to journalArticlepeer-review

Abstract

The nebular spectra of the broad-lined, Type Ic SN 2002ap are studied by means of synthetic spectra. Two different modeling techniques are employed. In one technique, the SN ejecta are treated as a single zone, while in the other a density and abundance distribution in velocity is used from an explosion model. In both cases, heating caused by γ-ray and positron deposition is computed (in the latter case using a Monte Carlo technique to describe the propagation of γ-rays and positrons), as is cooling via forbidden-line emission. The results are compared, and although general agreement is found, the stratified models are shown to reproduce the observed line profiles much more accurately than the single-zone model. The explosion produced ∼0.1M of 56Ni. The distribution in velocity of the various elements is in agreement with that obtained from the early-time models, which indicated an ejected mass of ∼2.5 M with a kinetic energy of 4 × 1051 erg. Nebular spectroscopy confirms that most of the ejected mass (∼1.2 M) was oxygen. The presence of an oxygen-rich inner core, combined with that of 56Ni at high velocities as deduced from early-time models, suggests that the explosion was asymmetric, especially in the inner part.

Original languageEnglish (US)
Pages (from-to)592-599
Number of pages8
JournalAstrophysical Journal
Volume670
Issue number1
DOIs
StatePublished - Nov 20 2007

Keywords

  • Gamma rays: bursts
  • Nuclear reactions, nucleosynthesis, abundances
  • Supernovae: general
  • Supernovae: individual (SN 2002ap)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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