发表机构
Alma Mater Studiorum – Università di Bologna; INAF, Osservatorio di Astrofisica e Scienza dello Spazio; INFN, Sezione di Bologna; INAF - IRA; Universidad Nacional Autónoma de México; Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México（博洛尼亚大学; 意大利国家天体物理研究所天文与空间科学观测站; 意大利国家核物理研究所博洛尼部分部; 意大利国家天体物理研究所射电天文学研究所; 墨西哥国立自治大学; 墨西哥国立自治大学核科学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过模拟后并合星系团，提出扩展磁场功率谱模型，结合马尔可夫链蒙特卡洛拟合，发现磁场功率谱与局部ICM密度和团块度显著相关，有助于解释法拉第旋转观测。
AI 中文摘要
得益于当前和未来的射电干涉仪，法拉第旋转测量图已延伸至星系团的外围区域。通过磁场功率谱模型的解释，这些图可以为星系团内介质（ICM）的磁场性质提供严格的约束。我们的目标是确定在一个由最先进的无辐射宇宙磁流体动力学模拟中形成的后并合星系团中，磁场功率谱如何随ICM的环境和动力学变化。我们将模拟的星系团划分为边长950千秒差距的立方子盒，并计算每个子盒中的动能和磁能功率谱。从先前工作中提出的“仅发电机”函数形式出发，该形式用于描述由小尺度发电机放大的磁场涨落，我们引入了一个额外的类科尔莫戈罗夫分量，以考虑未放大磁场斑块的贡献。我们使用马尔可夫链蒙特卡洛方法，将这一扩展模型分别拟合到每个子盒的磁场功率谱中，并检查推断参数与相应子盒中评估的局部ICM性质之间的散点图。扩展模型在大多数子盒中能很好地再现磁场功率谱数据，而“仅发电机”模型仅在距离中心不太远的子盒中能很好地拟合这些数据。推断参数表现出显著的自子盒到子盒的变化，这些变化与局部ICM密度和团块度显著相关。这些相关性表明，磁场功率谱与局部ICM环境密切相关，并可能有助于观测者解释法拉第旋转数据。
英文摘要
Thanks to the current and forthcoming radio interferometers, Faraday rotation measure maps extend out to the outskirts of galaxy clusters. Interpreted through models of the magnetic power spectrum, these maps can provide stringent constraints on the properties of the magnetic field of the intracluster medium (ICM). Our goal is to ascertain how the magnetic power spectrum varies with the environment and dynamics of the ICM in a post-merger galaxy cluster formed in a state-of-the-art non-radiative cosmological magneto-hydrodynamic simulation. We divide the simulated cluster into cubic subboxes with side length 950 kpc and compute the kinetic and magnetic power spectra in each. Starting from a "dynamo-only" functional form proposed in previous works to describe magnetic fluctuations amplified by the small-scale dynamo, we introduce an additional Kolmogorov-like component to account for the contribution of unamplified magnetic field patches. We fit this extended model to the magnetic power spectrum of each subbox individually using a Markov chain Monte Carlo method and examine scatter plots of the inferred parameters versus the local ICM properties evaluated in the corresponding subboxes. The extended model reproduces the magnetic power spectrum data well in most subboxes, whereas the "dynamo-only" model fits these data well only in subboxes not too far from the center. The inferred parameters exhibit substantial subbox-to-subbox variations that correlate significantly with the local ICM density and clumpiness. These correlations suggest that the magnetic power spectrum is closely linked to the local ICM environment, and may help observers in the interpretation of Faraday Rotation data.
CommentsSubmitted to A&A. 17 pages. 16 figures
