arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2402.01541astro-ph.GAastro-ph.HE
收藏

星暴星系的星系泡:星系大尺度磁场的影响

The galactic bubbles of starburst galaxies The influence of galactic large-scale magnetic fields

Z. Meliani, P. Cristofari, A. Rodriguez-Gonzalez, G. Fichet de Clairfontaine, E. Proust, E. Peretti

AI总结:

本研究通过磁流体动力学模拟探究大尺度磁场对星暴星系风泡演化的影响,发现磁场会改变泡的结构但无法单独解释M82等星系的观测特征,同时指出风终止激波是高能粒子加速的潜在位点。

摘要:

研究背景:星暴星系(SBGs)的星系风会在千秒差距尺度上形成显著结构,但这些巨型风泡的演化、形态及其产生的激波特性尚未被完全理解。研究目的:我们旨在探究星暴星系星系风的塑造机制,重点关注大尺度磁场在星系风膨胀形成的泡的动力学演化中的作用,此外还将探索这些系统中满足高效粒子加速条件的区域。研究方法:我们使用AMRVAC代码(自适应网格细化通用平流代码)开展了磁流体动力学模拟,设置了星系介质密度分布和磁化强度的多种构型。研究结果:我们发现,星系风在其中膨胀的大尺度磁场会影响膨胀泡的结构与演化,但星暴星系(如M82)中观测到的典型结构无法仅通过已考虑的磁场结构来解释,这凸显了星系盘等其他因素在塑造星系泡中的重要性。此外,在我们研究的所有磁化情形中,膨胀泡产生的前向波仅形成压缩波,而风终止激波具有高马赫数,是有望实现最高约10² PeV的扩散激波加速的位点。从我们的模型生成的合成X射线图像显示,泡周围存在一个延伸至2千秒差距的包层,这可能对应于M82中从平面几何结构观测到的偏振辐射,同时泡内部还有一个对应于受激星系风的大尺度结构。

英文摘要:

Context. The galactic winds of starburst galaxies (SBGs) give rise to remarkable structures on kiloparsec scales. However, the evolution and shape of these giant wind bubbles, as well as the properties of the shocks they develop, are not yet fully understood. Aims. We aim to understand what shapes the galactic winds of SBGs, with a particular focus on the role of large-scale magnetic fields in the dynamical evolution of galactic wind-inflated bubbles. In addition, we aim to explore where the conditions for efficient particle acceleration are met in these systems. Methods. We performed magnetohydrodynamic simulations with the AMRVAC code (Adaptive Mesh Refinement Versatile Advection Code) with various configurations of the galactic medium density profile and magnetization. Results. We observe that the large-scale magnetic field, in which galactic winds expand, can impact the structure and evolution of inflated bubbles. However, the typical structures observed in starburst galaxies, such as M82, cannot be solely explained by the magnetic field structures that have been considered. This highlights the importance of other factors, such as the galactic disk, in shaping the galactic bubble. Furthermore, in all the magnetized cases we investigated, the forward wave resulting from the expanding bubbles only results in compression waves, whereas the wind termination shock features high Mach numbers, making it a promising site for diffusive shock acceleration up to $\sim 10^{2}$ PeV. The synthetic X-ray images generated from our models reveal an envelope surrounding the bubbles that extends up to 2 kpc, which could correspond to the polarized emission observed from planar geometry in M82, as well as a large structure inside the bubble corresponding to the shocked galactic wind.

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。

↑