论文标题
仔细观察超新星作为银河磁化的种子
A closer look at supernovae as seeds for galactic magnetization
论文作者
论文摘要
解释星系中当前观察到的磁场需要在早期宇宙中相对较强的播种。一种理论提出，在恒星内部的原始，NG或较弱的场后，超新星（SN）爆炸驱逐了$μ$ G的磁场。在这项工作中，我们根据目前对恒星磁性的质量$ m_ {cl} $的恒星群集来计算可以在星际介质中注入的最大磁能。我们考虑早期型明星，并采用Salpeter或顶级IMF。对于它们的磁场，我们采用高斯或双峰分布。高斯模型假设所有巨大的恒星都被$ 10^3 <\ langle b_* \ rangle <10^4 $ g <10^4 $ g，而双峰却与对银河系恒星的观察一致，只有5-10％的ob恒星$ 10^3 <\ langle b_* \ lang b_* \ rangle <10^4 $ g，而REST <10^4 $ 10 < <10^2 $ g。我们发现，恒星种群可以注入的最大磁能在$ 10^{ - 10} -10} -10^{ - 7} $乘以总SN能量的乘以。这些估计值的最高端是比宇宙学模拟中通常使用的数量级低五个数量级，在宇宙学模拟中，SN能量的$ 10^{-2} $被注入磁性。 SN爆炸对恒星磁场的纯对流是播种发电机的良好候选者，但不足以使星系磁化。在最佳场景中，假设磁场作为银河磁化的主要机制，磁场的强度不能超过$ 10^{ - 7} $ g的强度，对于$ 10^{5} $ solar Mosses的人来说，磁场的强度不得超过300 pc radius的$ 10^{5} $太阳能，而更多的典型值则在$ 10^{-10^{-10^{-10} {-10} -10} -10} -10} -10^-9} $ g之间。因此，需要探索在高红移时进行银河系磁化的其他方案。
Explaining the currently observed magnetic fields in galaxies requires relatively strong seeding in the early Universe. One theory proposes that magnetic fields of the order of $μ$G were expelled by supernova (SN) explosions after primordial, nG or weaker fields were amplified in stellar interiors. In this work, we calculate the maximum magnetic energy that can be injected in the interstellar medium by a stellar cluster of mass $M_{cl}$ based on what is currently known about stellar magnetism. We consider early-type stars and adopt either a Salpeter or a top-heavy IMF. For their magnetic fields, we adopt either a Gaussian or a bimodal distribution. The Gaussian model assumes that all massive stars are magnetized with $10^3 < \langle B_* \rangle < 10^4$ G, while the bimodal, consistent with observations of Milky Way stars, assumes only 5-10 per cent of OB stars have $10^3 < \langle B_* \rangle < 10^4$ G, while the rest have $10 < \langle B_* \rangle < 10^2$ G. We find that the maximum magnetic energy that can be injected by a stellar population is between $10^{-10}-10^{-7}$ times the total SN energy. The highest end of these estimates is about five orders of magnitude lower than what is usually employed in cosmological simulations, where about $10^{-2}$ of the SN energy is injected as magnetic. Pure advection of the stellar magnetic field by SN explosions is a good candidate for seeding a dynamo, but not enough to magnetize galaxies. Assuming SNe as main mechanism for galactic magnetization, the magnetic field cannot exceed an intensity of $10^{-7}$ G in the best-case scenario for a population of $10^{5}$ solar masses in a superbubble of 300 pc radius, while more typical values are between $10^{-10}-10^{-9}$~G. Therefore, other scenarios for galactic magnetization at high redshift need to be explored.
