arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0804.3700astro-ph
收藏

核塌缩超新星的三维磁流体动力学模拟

Three Dimensional Magnetohydrodynamical Simulations of Core Collapse Supernova

Hayato Mikami, Yuji Sato, Tomoaki Matsumoto, Tomoyuki Hanawa

摘要:

我们对具有倾斜于自转轴的磁场的核心坍缩超新星进行了三维磁流体动力学模拟。模拟采用了一个简单的经验状态方程,其中简并气体的压力近似为分段多面体为简单。为了简单起见,没有考虑中微子引起的能量损失。模拟从一个铁芯的动态崩溃阶段开始。在高密度气体的压力作用下,动力学坍缩在$ t $ = 189 ms时停止,形成原中子星(PNS)。在典型的模型中,PNS的演变约为40毫秒。当初始旋转是适度的快和初始磁场是适度的强,双极喷流发射从高层大气($ r \sim 60 {\rm km} $)的PNS。喷流被加速到$ \sim 3 \times 10 ^4 $ km s $^{-1}$,这与足点处的逃逸速度相当。射流平行于初始旋转轴线。在喷射之前,磁场通过PNS的旋转而扭曲。扭曲的磁场形成环形多层膜,其中方位分量交替变化。磁性多层膜的形成是由于初始条件,其中磁场相对于旋转轴倾斜。喷流的能量仅微弱地依赖于假定的初始磁场。当初始磁场较弱时,PNS形成和喷流喷射之间的时滞较长。它还表明,时滞有关的阿尔文渡越时间。虽然在我们的模拟中,近球形的瞬发激波向外传播,但它是…

英文摘要:

We show three-dimensional magnetohydrodynamical simulations of core collapse supernova in which the progenitor has magnetic fields inclined to the rotation axis. The simulations employed a simple empirical equation of state in which the pressure of degenerate gas is approximated by piecewise polytropes for simplicity. Neither energy loss due to neutrino is taken into account for simplicity. The simulations start from the stage of dynamical collapse of an iron core. The dynamical collapse halts at $ t $ = 189 ms by the pressure of high density gas and a proto-neutron star (PNS) forms. The evolution of PNS was followed about 40 milli-seconds in typical models. When the initial rotation is mildly fast and the initial magnetic fields are mildly strong, bipolar jets are launched from an upper atmosphere ($ r \sim 60 {\rm km} $) of the PNS. The jets are accelerated to $ \sim 3 \times 10 ^4 $ km s$^{-1}$, which is comparable to the escape velocity at the foot point. The jets are parallel to the initial rotation axis. Before the launch of the jets, magnetic fields are twisted by rotation of the PNS. The twisted magnetic fields form torus-shape multi-layers in which the azimuthal component changes alternately. The formation of magnetic multi-layers is due to the initial condition in which the magnetic fields are inclined with respect to the rotation axis. The energy of the jet depends only weakly on the initial magnetic field assumed. When the initial magnetic fields are weaker, the time lag is longer between the PNS formation and jet ejection. It is also shown that the time lag is related to the Alfvén transit time. Although the nearly spherical prompt shock propagates outward in our simulations, it is ...

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。

↑