Radio Supernova SN 1998bw and Its Relation to GRB 980425
Radio Supernova SN 1998bw and Its Relation to GRB 980425
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DOI：
10.1086/308031
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发表时间：
1999-03
期刊：
影响因子：
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通讯作者：
Zhi-Yun Li;R. Chevalier
中科院分区：
文献类型：
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作者：
Zhi-Yun Li;R. Chevalier
SN 1998bw 是一颗不寻常的 Ic 型超新星，可能与 γ 射线爆发 GRB 980425 有关。我们使用同步加速器自吸收模型对其射电发射进行推断，推断出同步加速器发射气体正在以与光速相当的速度膨胀到密度剖面近似为 r-2 的星周介质中。我们假设相对论性电子和磁场的产生效率在演化过程中是恒定的。星周密度与被认为是 SN 1998bw 前身的大质量星核周围的预期一致。以大于 0.5c 的速度移动的材料的爆炸能量约为 1049 - (3 × 1050) 尔格，有些人倾向于选择较高的值。在第 20-40 天观察到的射电光变曲线的上升被推断是爆炸波能量上升约 2.5 倍的结果。与环境密度跳跃的相互作用与观察到的演化不一致。我们推断，能量的增加来自爆炸产生的物质壳，它赶上了减速的激波前沿。高爆炸能量和冲击波能量输入的性质都很难与超新星冲击加速高速喷射物输入的能量相协调。这意味着中央引擎存在不规则的能量输入，这是为正常 γ 射线爆发调用的模型类型。 SN 1998bw 和 GRB 980425 之间的联系因此得到加强。
SN 1998bw is an unusual Type Ic supernova that may be associated with the γ-ray burst GRB 980425. We use a synchrotron self-absorption model for its radio emission to deduce that the synchrotron-emitting gas is expanding into a circumstellar medium of approximately r-2 density profile at a speed comparable to the speed of light. We assume that the efficiencies of production of relativistic electrons and magnetic field are constant through the evolution. The circumstellar density is consistent with that expected around the massive star core thought to be the progenitor of SN 1998bw. The explosion energy in material moving with velocity greater than 0.5c is ~1049 - (3 × 1050) ergs, with some preference for the high values. The rise in the radio light curves observed at days 20-40 is inferred to be the result of a rise in the energy of the blast wave by a factor of ~2.5. Interaction with a jump in the ambient density is not consistent with the observed evolution. We infer that the boost in energy is from a shell of matter from the explosion that catches up with the decelerating shock front. Both the high explosion energy and the nature of the energy input to the blast wave are difficult to reconcile with energy input from the shock-accelerated high-velocity ejecta from a supernova. The implication is that there is irregular energy input from a central engine, which is the type of model invoked for normal γ-ray bursts. The link between SN 1998bw and GRB 980425 is thus strengthened.