Raynaud Raphaël, Guilet Jérôme, Janka Hans-Thomas, Gastine Thomas
AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, F-91191 Gif-sur-Yvette, France.
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching, Germany.
Sci Adv. 2020 Mar 13;6(11):eaay2732. doi: 10.1126/sciadv.aay2732. eCollection 2020 Mar.
The release of spin-down energy by a magnetar is a promising scenario to power several classes of extreme explosive transients. However, it lacks a firm basis because magnetar formation still represents a theoretical challenge. Using the first three-dimensional simulations of a convective dynamo based on a protoneutron star interior model, we demonstrate that the required dipolar magnetic field can be consistently generated for sufficiently fast rotation rates. The dynamo instability saturates in the magnetostrophic regime with the magnetic energy exceeding the kinetic energy by a factor of up to 10. Our results are compatible with the observational constraints on galactic magnetar field strength and provide strong theoretical support for millisecond protomagnetar models of gamma-ray burst and superluminous supernova central engines.
磁星释放的自转变慢能量是为几类极端爆发性瞬变现象提供能量的一种有前景的设想。然而，它缺乏坚实的基础，因为磁星的形成仍然是一个理论挑战。基于原中子星内部模型，利用对流发电机的前三维模拟，我们证明，对于足够快的旋转速率，可以持续产生所需的偶极磁场。发电机不稳定性在磁旋转平衡状态下达到饱和，磁能比动能高出多达10倍。我们的结果与银河系磁星场强的观测约束条件相符，并为伽马射线暴和超亮超新星中央引擎的毫秒级原磁星模型提供了有力的理论支持。
