Extreme Astrophysical Fluids, Magnetism and Radiation

极端天体物理流体、磁力和辐射

• 批准号: RGPIN-2017-06519
• 负责人: Thompson, Christopher
• 金额: $ 1.53万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=711816
• 关键词: Extreme; Astrophysical; Fluids; Magnetism; Radiation

This proposal addresses problems related to i) extreme astrophysical magnetism; ii) the interaction of fluids with intense radiation fields; and iii) the physics of solid-gas mixtures during planet formation. The PI has published in all these areas with post-docs and students over the last few years. 1. Magnetars. We recently developed a 2-dimensional numerical model of a neutron star crust that incorporates elastic, plastic, magnetic and thermal effects. This model makes distinct predictions for the origin of the bright broad-band electromagnetic emission of magnetars, which is powered by the decay of 1015 G magnetic fields. We will develop detailed spectral models using newly calculated QED rates, and further explore the predictions of the 2D plastic-thermal model for the decaying dissipative tails seen following outbursts. 2. Gamma-ray bursts. We recently developed the first self-consistent model of the prompt (0.1-100s) phase of a GRB that i) starts with a strongly magnetized outflow and ii) uses kinetic calculations to reproduce key observational features (a narrow spectral peak, non-thermal spectra tail, and hard-to-soft evolution). Distinct predictions of spectral features are mirrored in some recent data, which will be investigated in more detail. 3. Magnetized outflows containing intense radiation fields. We will investigate magnetocentrifugal flows from radiation-pressure dominated accretion disks, extending our previous calculations of jet acceleration. The wind torque will be calculated for a wide range of radial magnetic flux profiles, and applied to the global evolution of disks feeding hyper-accreting objects and supermassive black holes. 4. Coherent low-frequency emission from relativistic outflows. Models of pulsar radio emission generally posit that the emitting plasma is confined to the magnetosphere. We will develop alternative processes involving relativistically expanded magnetized shells, which may be relevant to the fast radio burst phenomenon. 5. Origin of magnetic fields in compact stars. We recently investigated the pumping of magnetic helicity at convective-radiative boundaries in evolved stars. This process will be extended to accreting stars, to address the magnetization of recycled pulsars, cataclysmic variables, and young, massive stars. 6. Extreme solid-gas mixtures. The assembly of planets must involve extreme states in which solids dominate the mass density and gas the pressure. Our 2014 calculation of shock behavior, including a detailed account of particle fragmentation and melting, will be applied to planetesimal/planet disk interaction. The model of a two-phase proto-lunar disk developed by Thompson & Stevenson will be adapted to more general conditions, with a focus on the role of phase exchange in facilitating outflows. The particle solver in the publicly available code ATHENA will be updated to include fragmentation effects.

该提案解决了与i）极端天体物理磁性有关的问题； ii）流体与强烈辐射场的相互作用； iii）星球形成期间固体气体混合物的物理。 在过去的几年中，PI在所有这些领域都在所有这些领域发表。 1。磁铁。 我们最近开发了一种二维数值模型的中子星形外壳，该模型融合了弹性，塑料，磁性和热效应。 该模型对磁铁的明亮宽带电磁发射的起源做出了不同的预测，该电磁体由1015 g磁场的衰减提供动力。 我们将使用新计算的QED速率开发详细的光谱模型，并进一步探索2D塑料热模型的预测，以探索以下爆发的衰减耗散尾巴。 2。伽马射线爆发。最近，我们开发了GRB的提示（0.1-100）阶段的第一个自洽模型，i）i）从强烈的流出开始，ii）ii）使用动力学计算来重现关键的观察特征（狭窄的光谱峰，非热光谱尾巴，无热光谱尾巴，硬到软的演变）。 在最近的一些数据中，对光谱特征的不同预测进行了反映，这将进行详细研究。 3。磁化的流出包含强烈的辐射场。 我们将研究来自辐射压缩磁盘的磁中心流动，从而扩展了我们先前的喷射加速度计算。 风转扭矩将用于广泛的径向磁通轮廓，并应用于圆盘的全局进化，以供应超磨碎的物体和超质量黑洞。 4。相对论流出的相干低频排放。 Pulsar无线电发射模型通常认为发射等离子体局限于磁层。 我们将开发涉及相对扩展的磁化壳的替代过程，这可能与快速无线电爆发现象有关。 5。紧凑型恒星中磁场的起源。最近，我们研究了进化恒星中对流辐射边界处的磁性螺旋度的泵送。 该过程将扩展到吸收恒星，以解决可回收的脉冲星，灾难性变量和年轻巨大恒星的磁化。 6。极端气体混合物。行星的组装必须涉及极端状态，其中固体主导质量密度和气体压力。我们2014年对冲击行为的计算，包括粒子碎片和熔化的详细说明，将应用于行星/行星磁盘相互作用。 由汤普森（Thompson）和史蒂文森（Stevenson）开发的两阶段原型磁盘的模型将适应更一般的条件，重点是相位交换在促进流出中的作用。 雅典娜公共代码中的粒子求解器将被更新，以包括分裂效果。