Neutrino-driven Convection versus Advection in Core-Collapse Supernovae
Neutrino-driven Convection versus Advection in Core-Collapse Supernovae
复制标题
核心塌陷超新星中中微子驱动的对流与平流
DOI：
10.1086/508443
复制
发表时间：
2005
期刊：
影响因子：
--
通讯作者：
H. Janka
中科院分区：
文献类型：
--
作者：
T. Foglizzo;L. Scheck;H. Janka
一个玩具模型进行了分析，以评估的线性稳定性的增益区后立即停滞吸积冲击，核心反弹。这个模型表明，负熵梯度不足以保证线性不稳定性。稳定性准则由通过增益区的平流时间除以浮力的局部时间尺度的比率χ决定。如果χ < 3，则增益区域线性稳定。经典对流不稳定性在χ = 3的极限下得到恢复。对于χ > 3，扰动在以增益区域的垂直尺寸H的两倍为中心的有限水平波长范围内是不稳定的。阈值水平波数kmin和kmax遵循简单的标度律，使得Hkmin = 1/x并且Hkmax = 1/x。本文讨论了球形吸积中l = 1模的对流稳定性，并与核塌缩超新星的非对称爆炸有关。长波长扰动的平流稳定减弱了对流单独对全球l = 1模式的可能影响。
A toy model is analyzed in order to evaluate the linear stability of the gain region immediately behind a stalled accretion shock, after core bounce. This model demonstrates that a negative entropy gradient is not sufficient to warrant linear instability. The stability criterion is governed by the ratio χ of the advection time through the gain region divided by the local timescale of buoyancy. The gain region is linearly stable if χ < 3. The classical convective instability is recovered in the limit χ ≫ 3. For χ > 3, perturbations are unstable in a limited range of horizontal wavelengths centered around twice the vertical size H of the gain region. The threshold horizontal wavenumbers kmin and kmax follow simple scaling laws such that Hkmin ∝ 1/χ and Hkmax ∝ χ. The convective stability of the l = 1 mode in spherical accretion is discussed, in relation with the asymmetric explosion of core-collapse supernovae. The advective stabilization of long-wavelength perturbations weakens the possible influence of convection alone on a global l = 1 mode.