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 2102.03362astro-ph.GA
收藏

M82星系外流磁场的强度和结构

The strength and structure of the magnetic field in the galactic outflow of M82

Enrique Lopez-Rodriguez, Jordan Guerra, Mahboubeh Asgari-Targhi, Joan T. Schmelz

摘要:

由星爆驱动的星系外流可以改变星系磁场,使它们远离星系平面。在这里,我们量化这些领域可能磁化星系际介质。我们估计的强度和结构的恒星爆发星系M82使用热偏振发射观测SOFIA/HAWC+和太阳物理学中常用的潜在的场外推。我们修改了Davis-Ehrasekhar-Fermi方法,以考虑大尺度流动和湍流场。结果表明,所观察到的磁场产生的组合的大规模有序的位场与流出和小规模的湍流场与弓形激波的功能。在中心$900$ pc半径内,大尺度磁场占观测到的湍流磁能的$53\pm4$ %,中值场强为$305\pm15$ $μ$ G,而小尺度湍流磁场占剩余的$40\pm5$ %,中值场强为$222\pm19$ $μ$ G。我们估计,湍流动能和湍流磁能接近均分高达$\sim2$ kpc(测量),而湍流动能占主导地位的$\sim7$ kpc(外推)。我们的结论是,该领域冻结到电离流出介质和驱动离开动力学。M82星系风中的磁场线是“开放的”,在星暴核心和星系际介质之间提供了一个直接的通道。我们的新方法提供了量化外流对星系磁场的影响以及它们对星系际介质和高能粒子演化的影响所需的工具。

英文摘要:

Galactic outflows driven by starbursts can modify the galactic magnetic fields and drive them away from the galactic planes. Here, we quantify how these fields may magnetize the intergalactic medium. We estimate the strength and structure of the fields in the starburst galaxy M82 using thermal polarized emission observations from SOFIA/HAWC+ and a potential field extrapolation commonly used in solar physics. We modified the Davis-Chandrasekhar-Fermi method to account for the large-scale flow and the turbulent field. Results show that the observed magnetic fields arise from the combination of a large-scale ordered potential field associated with the outflow and a small-scale turbulent field associated with bow-shock-like features. Within the central $900$ pc radius, the large-scale field accounts for $53\pm4$% of the observed turbulent magnetic energy with a median field strength of $305\pm15$ $μ$G, while small-scale turbulent magnetic fields account for the remaining $40\pm5$% with a median field strength of $222\pm19$ $μ$G. We estimate that the turbulent kinetic and turbulent magnetic energies are in close equipartition up to $\sim2$ kpc (measured), while the turbulent kinetic energy dominates at $\sim7$ kpc (extrapolated). We conclude that the fields are frozen into the ionized outflowing medium and driven away kinetically. The magnetic field lines in the galactic wind of M82 are `open,' providing a direct channel between the starburst core and the intergalactic medium. Our novel approach offers the tools needed to quantify the effects of outflows on galactic magnetic fields as well as their influence on the intergalactic medium and evolution of energetic particles.

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。

↑