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arXiv 1606.02501astro-ph.HEastro-ph.GA
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星际介质结构与超新星遗迹射电$Σ-D$关系的斜率

Interstellar medium structure and the slope of the radio $Σ-D$ relation of supernova remnants

Petar Kostić, Branislav Vukotić, Dejan Urošević, Bojan Arbutina, Tijana Prodanović

摘要:

分析了星际物质密度分形结构对超新星遗迹射电表面亮度与直径关系参数值的影响。我们将密集ISM模型化为具有分形密度结构的分子云。SNR被建模为散布在建模ISM中的不同半径的球体。SNR的表面亮度由简单的关系式$Σ\propto ρ^{0.5}D^{-3.5}$以及参数化的更一般的形式$Σ\propto ρ^ηD^{-β_0}$计算。我们的研究结果表明,经验$Σ-D$的斜率比理论推导的斜率更陡,这可能部分地解释了SNR扩展到环境介质的分形结构。如果形成SNR的区域的密度较高,则$Σ-D$关系的斜率变陡。简单的几何效应与ISM的分形结构相结合,可以导致更陡的经验$Σ-D$斜率,特别是对于较老的遗迹,如果$Σ$对环境密度有更强的依赖性,这一点会更加明显。

英文摘要:

We analyze the influence of fractal structure of the interstellar matter (ISM) density on the parameter values for the radio surface brightness to diameter ($Σ-D$) relation for supernovae remnants (SNRs). We model a dense ISM as a molecular cloud with fractal density structure. SNRs are modelled as spheres of different radius scattered in the modelled ISM. The surface brightness of the SNRs is calculated from the simple relation $Σ\propto ρ^{0.5}D^{-3.5}$ and also from the parametrized more general form $Σ\propto ρ^ηD^{-β_0}$. Our results demonstrate that empirical $Σ-D$ slopes that are steeper than the ones derived from theory, might be partly explained with the fractal structure of the ambient medium into which SNRs expand. The slope of the $Σ-D$ relation steepens if the density of the regions where SNRs are formed is higher. The simple geometrical effects combined with the fractal structure of the ISM can contribute to a steeper empirical $Σ-D$ slopes, especially for older remnants, and this is more pronounced if $Σ$ has a stronger dependence on ambient density.

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