Evidence for past interaction with an asymmetric circumstellar shell in the young SNR Cassiopeia A
Evidence for past interaction with an asymmetric circumstellar shell in the young SNR Cassiopeia A
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年轻 SNR 仙后座 A 中过去与不对称星周壳相互作用的证据
DOI：
10.1051/0004-6361/202243258
复制
发表时间：
2022
影响因子：
6.5
通讯作者：
Peres G.
中科院分区：
文献类型：
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作者：
Orlando S.;Wongwathanarat A.;Janka H.-T.;Miceli M.;Nagataki S.;Ono M.;Bocchino F.;Vink J.;Milisavljevic D.;Patnaude D. J.;Peres G.
对超新星遗迹仙后座A（Cassiopeia A）的观测表明，在反向激波中存在着明显的不对称性，这一现象不能用描述遗迹通过祖先星星的球对称风膨胀的模型来解释。目的我们研究过去CasA与星周介质的大质量非对称壳层的相互作用是否可以解释所观测到的反向激波的不对称性。三维（3D）（磁）流体动力学模拟，描述了从SN爆炸到其与大质量拱壳相互作用的残留物演变。初始条件（在恒星表面的冲击爆发后不久）提供了一个三维中微子驱动的SN模型，其形态非常类似于Cas A和SNR模拟涵盖2000年的演变。我们探索了壳层的参数空间，寻找一组能够在遗迹的西半球产生一个向内运动的反向冲击的参数，结果如果壳体与反激波中的残壳部分不对称，则残壳与壳体的相互作用可以产生类似于反激波中观察到的不对称性。（蓝移）向西北方（NW）。根据我们最喜欢的模型，炮弹很薄（厚度为0.02 pc），距离爆炸中心的半径为1.5 pc。反向激波在Cas A时代表现出以下不对称性：（1）在观测坐标系中，反向激波在NW区向内移动，而在其它大部分区域向外移动;（2）反向激波的几何中心相对于正向激波的几何中心向NW方向偏移0.1pc;和（iii）在西北地区的反向冲击增强了非热发射，因为，在那里，喷出物以较高的相对速度进入反向激波（在4000和7000 km s-1之间）（低于2000 km s-1）。在Cas A的反向激波中观察到的尺度不对称性，可以解释为在20180年至20240年之间，残留物与不对称的致密星周壳层相互作用的特征在SN事件之后。我们认为，壳层很可能是在核心坍缩前104年至105年发生的祖先星星大规模喷发的结果。我们估计壳层的总质量约为2 M Ω。
ContextObservations of the supernova remnant (SNR) Cassiopeia A (Cas A) show significant asymmetries in the reverse shock that cannot be explained by models describing a remnant expanding through a spherically symmetric wind of the progenitor star.AimsWe investigate whether a past interaction of Cas A with a massive asymmetric shell of the circumstellar medium can account for the observed asymmetries of the reverse shock.MethodsWe performed three-dimensional (3D) (magneto)-hydrodynamic simulations that describe the remnant evolution from the SN explosion to its interaction with a massive circumstellar shell. The initial conditions (soon after the shock breakout at the stellar surface) are provided by a 3D neutrino-driven SN model whose morphology closely resembles Cas A and the SNR simulations cover ≈2000 yr of evolution. We explored the parameter space of the shell, searching for a set of parameters able to produce an inward-moving reverse shock in the western hemisphere of the remnant at the age of ≈350 yr, analogous to that observed in Cas A.ResultsThe interaction of the remnant with the shell can produce asymmetries resembling those observed in the reverse shock if the shell was asymmetric with the densest portion in the (blueshifted) nearside to the northwest (NW). According to our favorite model, the shell was thin (thicknessσ≈ 0.02 pc) with a radiusrsh≈ 1.5 pc from the center of the explosion. The reverse shock shows the following asymmetries at the age of Cas A: (i) it moves inward in the observer frame in the NW region, while it moves outward in most other regions; (ii) the geometric center of the reverse shock is offset to the NW by ≈0.1 pc from the geometric center of the forward shock; and (iii) the reverse shock in the NW region has enhanced nonthermal emission because, there, the ejecta enter the reverse shock with a higher relative velocity (between 4000 and 7000 km s−1) than in other regions (below 2000 km s−1).ConclusionsThe large-scale asymmetries observed in the reverse shock of Cas A can be interpreted as signatures of the interaction of the remnant with an asymmetric dense circumstellar shell that occurred between ≈180 and ≈240 yr after the SN event. We suggest that the shell was, most likely, the result of a massive eruption from the progenitor star that occurred between 104and 105yr prior to core-collapse. We estimate a total mass of the shell of the order of 2M⊙.
仙后座 A 揭示了过去与星周壳的相互作用
DOI：
--
发表时间：
2022
期刊：
--
影响因子：
--
作者：
S. Orlando;A. Wongwathanarat;H. Janka;M. Miceli;S. Nagataki;M. Ono;F. Bocchino;J. Vink;D. Milisavljevic;D. Patnaude;G. Peres
通讯作者：
G. Peres
影响因子：
5.2
作者：
A. Maeder;A. Renzini
通讯作者：
A. Renzini