Dust in the wind with resonant drag instabilities – I. The dynamics of dust-driven outflows in GMCs and H ii regions
Dust in the wind with resonant drag instabilities – I. The dynamics of dust-driven outflows in GMCs and H ii regions
复制标题
具有共振阻力不稳定性的风中的灰尘 I. GMC 和 H ii 区域中灰尘驱动的外流动态
DOI：
10.1093/mnras/stac1784
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发表时间：
2022
影响因子：
4.8
通讯作者：
Steinwandel, Ulrich P.
中科院分区：
文献类型：
--
作者：
Hopkins, Philip F.;Rosen, Anna L.;Squire, Jonathan;Panopoulou, Georgia V.;Soliman, Nadine H.;Seligman, Darryl;Steinwandel, Ulrich P.
辐射尘埃驱动的外流，其中尘埃颗粒上的辐射压力加速气体，发生在许多天体物理环境中。几乎所有以前对这些系统的数值研究都假设尘埃与气体完全耦合。然而，它最近已被证明，在这些系统中的灰尘是不稳定的一大类的“共振阻力不稳定性”（RDIs），解耦的灰尘和气体动力学，并可以定性地改变这些流出的非线性结果。我们提出的第一个模拟辐射尘埃驱动的外流分层，不均匀的介质，包括明确的颗粒动力学和现实的光谱的颗粒大小和电荷，磁场和洛伦兹力的颗粒（显着提高RDI），库仑和爱泼斯坦阻力，并明确的辐射传输允许不同的颗粒吸收和散射特性。在本文中，我们考虑类似于巨分子云（GMC），Hiiregions和分布式星爆的条件，光学厚度适中（1001），单散射效应主导辐射尘埃耦合，洛伦兹力主导颗粒阻力，增长最快的RDI是相似的，如磁声和快速陀螺RDI。这些RDIs一般产生强大的大小依赖的灰尘集群，增长非线性的时间尺度上是远远短于流出的特征时间。这种不稳定性产生了类似羽状或马头状星云的形态，与在GMC和Hiiregions观测到的尘埃结构非常相似。此外，在某些情况下，它们强烈地改变磁场结构和相对于灯丝的拓扑结构。尽管驱动强大的微尺度灰尘结块，留下一些气体“后面”，一个有序的统一部分的气体总是有效地夹带灰尘。
Radiation-dust driven outflows, where radiation pressure on dust grains accelerates gas, occur in many astrophysical environments. Almost all previous numerical studies of these systems have assumed that the dust was perfectly coupled to the gas. However, it has recently been shown that the dust in these systems is unstable to a large class of ‘resonant drag instabilities’ (RDIs) which de-couple the dust and gas dynamics and could qualitatively change the non-linear outcome of these outflows. We present the first simulations of radiation-dust driven outflows in stratified, inhomogeneous media, including explicit grain dynamics and a realistic spectrum of grain sizes and charge, magnetic fields and Lorentz forces on grains (which dramatically enhance the RDIs), Coulomb and Epstein drag forces, and explicit radiation transport allowing for different grain absorption and scattering properties. In this paper, we consider conditions resembling giant molecular clouds (GMCs), Hiiregions, and distributed starbursts, where optical depths are modest (≲1), single-scattering effects dominate radiation-dust coupling, Lorentz forces dominate over drag on grains, and the fastest-growing RDIs are similar, such as magnetosonic and fast-gyro RDIs. These RDIs generically produce strong size-dependent dust clustering, growing non-linear on time-scales that are much shorter than the characteristic times of the outflow. The instabilities produce filamentary and plume-like or ‘horsehead’ nebular morphologies that are remarkably similar to observed dust structures in GMCs and Hiiregions. Additionally, in some cases they strongly alter the magnetic field structure and topology relative to filaments. Despite driving strong micro-scale dust clumping which leaves some gas ‘behind,’ an order-unity fraction of the gas is always efficiently entrained by dust.