由星云光谱推断的高能Ic型SN 2002 ap的非球面性质
The Aspherical Properties of the Energetic Type Ic SN 2002ap as Inferred from its Nebular Spectra
摘要：
本文用合成光谱的方法研究了宽线的类SN 1998 bw的Ic型SN 2002 ap的星云光谱。采用了两种不同的建模技术。在一种技术中，SN喷出物被视为一个单一的区域，而在另一个密度和丰度分布的速度是使用从爆炸模型。在这两种情况下，计算由伽马射线和正电子沉积引起的加热（在后一种情况下，使用蒙特卡罗技术来描述伽马射线和正电子的传播），以及通过禁止线发射的冷却。结果进行了比较，虽然一般协议被发现，分层模型所示的再现所观察到的线轮廓更准确地比单区模型。爆炸产生了约0.1 Msun的56 Ni。各种元素的速度分布与早期模型的结果一致，早期模型表明喷射质量约为2.5 Msun，动能为4 x 10^{51} erg。星云光谱学证实，大部分喷射的质量（约1.2 Msun）是氧气。富氧内核的存在，以及从早期模型推导出的56 Ni的高速，表明爆炸是不对称的，特别是在内部。
英文摘要：
The nebular spectra of the broad-lined, SN 1998bw-like Type Ic SN 2002ap are studied by means of synthetic spectra. Two different modelling 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 gamma-ray and positron deposition is computed (in the latter case using a Monte Carlo technique to describe the propagation of gamma-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 ~ 0.1 Msun 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 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 of 56Ni at high velocities as deduced from early-time models, suggests that the explosion was asymmetric, especially in the inner part.
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