Dwarf nova outbursts with magnetorotational turbulence
Dwarf nova outbursts with magnetorotational turbulence
复制标题
矮新星爆发磁旋转湍流
DOI：
10.1093/mnras/stw1908
复制
发表时间：
2016
影响因子：
4.8
通讯作者：
S. Hirose
中科院分区：
文献类型：
--
作者：
M. S. B. Coleman;I. Kotko;O. Blaes;J.-P. Lasota;S. Hirose
现象学盘不稳定性模型通过调用增强的Shakura-Sunyaev α参数（爆发时为~ 0.1-0.2，而静止时为低值~ 0.01）成功地再现了观测到的矮新星爆发的光曲线。最近对矮新星吸积盘适当不透明的磁旋不稳定性（MRI）湍流的热力学一致性模拟和状态方程发现，热对流增强了爆发时盘中的α，但仅在氢电离跃迁附近。在较高的温度下，对流不再存在，α返回到与静止时相当的低值。为了验证氢电离跃迁附近的这种增强是否足以重现观测到的光曲线，我们将这种基于核磁共振成像的α变化纳入了圆盘不稳定性模型，以及基于湍流耗散和对流输运的模拟模型。这些基于核磁共振成像的模型可以成功地再现观察到的突出和静止持续时间，以及突出幅度，尽管与标准圆盘不稳定模型的参数不同。基于核磁共振成像（mri）的模型光曲线显示出在爆发后的衰减中出现的再闪光，这在矮新星中是不常见的。然而，我们强调了在椎间盘不稳定模型和MRI模拟中引起这种行为的静止物理问题。
The phenomenological disc instability model has been successful in reproducing the observed light curves of dwarf nova outbursts by invoking an enhanced Shakura–Sunyaev α parameter ∼0.1–0.2 in outburst compared to a low value ∼0.01 in quiescence. Recent thermodynamically consistent simulations of magnetorotational instability (MRI) turbulence with appropriate opacities and equation of state for dwarf nova accretion discs have found that thermal convection enhances α in discs in outburst, but only near the hydrogen ionization transition. At higher temperatures, convection no longer exists and α returns to the low value comparable to that in quiescence. In order to check whether this enhancement near the hydrogen ionization transition is sufficient to reproduce observed light curves, we incorporate this MRI-based variation in α into the disc instability model, as well as simulation-based models of turbulent dissipation and convective transport. These MRI-based models can successfully reproduce observed outburst and quiescence durations, as well as outburst amplitudes, albeit with different parameters from the standard disc instability models. The MRI-based model light curves exhibit reflares in the decay from outburst, which are not generally observed in dwarf novae. However, we highlight the problematic aspects of the quiescence physics in the disc instability model and MRI simulations that are responsible for this behaviour.