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arXiv 2209.12397astro-ph.HEgr-qc
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脉冲星风星云模型有多独特?多参数时变光谱自动拟合的实现

How unique are pulsar wind nebulae models? Implementation of a multi-parameter, automatic fitting for time-dependent spectra

J. Martin, D. F. Torres

摘要:

由于计算大量参数变化的计算成本,脉冲星风星云(PWNe)的详细辐射模型通常不包含拟合算法。因此,文献中的大多数模型实际上是基于目视检查的定性拟合。当考虑复杂的、时间依赖的模型时,这一点尤其正确。在过去几年中获得的当前PWN模型的计算效率的改进的动机,我们在这里探索纳入自动拟合算法到一个完全依赖于时间的模型。利用基于Nelder-Mead算法的有效拟合工具,采用含时辐射模型,对蟹状星云和3C 58进行了盲拟合,计算了年轻和中年PWNe的光谱和动力学演化.这种包含允许我们,除了更忠实地确定拟合的质量之外,还可以解决所选PWNe模型中是否存在简并。我们发现Crab和3C 58的拟合都很好,并且没有其他显着不同的模型参数集能够同样好地处理实验数据。该代码还能够将系统的年龄视为自由参数,从而根据年龄递归地确定所有其他所需的幅度。我们使用这个功能来考虑是否一个详细的多频光谱可以约束星云的年龄,发现事实上这是两个PWNe研究的情况。

英文摘要:

Due to the computational cost of calculating a great number of variations of the parameters, detailed radiative models of pulsar wind nebulae (PWNe) do not usually contain fitting algorithms. As a consequence, most of the models in the literature are, in fact, qualitative fits based on visual inspection. This is particularly true when complex, time-dependent models are considered. Motivated by improvements in the computational efficiency of the current PWN models that were obtained in the last years, we here explore the inclusion of automatic fitting algorithms into a fully time-dependent model. Incorporating an efficient fitting tool based on the Nelder-Mead algorithm, we blindly find fitting solutions for the Crab nebula and 3C 58 with a time-dependent radiation model to compute the spectral and dynamical evolution of young and middle-aged PWNe. This inclusion allows us, in addition of more faithfully determining the quality of the fit, to tackle whether there exist degeneracy in the selected PWNe models. We find both for Crab and 3C58, that the fits are well determined, and that no other significantly different set of model parameters is able to cope with experimental data equally well. The code is also able to consider the system's age as a free parameter, recursively determining all other needed magnitudes depending on age accordingly. We use this feature to consider whether a detailed multi-frequency spectra can constrain the nebula age, finding that in fact this is the case for the two PWNe studied.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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