Why Blazar Jets Shine: Radiative Relativistic Reconnection and the Minijet Model

Blazer 喷气机为何大放异彩：辐射相对论重联和迷你喷气机模型

基本信息

批准号：
1411879
负责人：
Mitchell Begelman
金额：
$ 69.88万
依托单位：
University of Colorado at Boulder
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2014
资助国家：
美国
起止时间：
2014-08-01 至 2019-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1411879&HistoricalAwards=false
关键词：
Why Blazar Jets Shine Radiative

项目摘要

Blazars are a subset of active galactic nuclei, which are highly energetic cores of galaxies, singled out by the fact that their jets of material, flowing out at speeds approaching that of light, just happen to be arranged so as to point towards us. As such, blazars provide a direct view of how energy is radiated away and degraded in and around fast moving plasmas. Unfortunately, the current explanations have proven inadequate. This research team has introduced a new model that looks very promising in initial, approximate, studies. This project will use new computational techniques to simulate the motions of large amounts of high-speed plasma, to study the problems in sufficient detail to distinguish between the possible alternatives by comparing with astronomical observations. The research tool developed for this work will be packaged for others to use in many areas of plasma science.Blazars are the primary sources of persistent extragalactic gamma-ray radiation detected by ground- and space-based observatories. They provide a direct view of dissipation and radiative processes in relativistic collisionless plasmas. Recent observations of rapid intense flares imply that the emitting regions are very compact and propagate with much higher Lorentz factors than the bulk jet values deduced from radio observations. A semi-analytical model using localized, relativistic sub-flows, called minijets, has reproduced the main features of flaring blazars, but is based on crude approximations. This project will use a new, fully radiative Particle-in-Cell (PIC) code to study collisionless reconnection in relativistic plasmas, including the effects that plasma magnetization, the strength of the magnetic guide field, and the plasma composition, can have on bulk plasma motions, particle acceleration, and radiative signatures. Simulated time-dependent spectra will be compared to existing data. The puzzling gamma-ray flares from the Crab Nebula cannot be due to shock acceleration or any other magnetohydrodynamic process, and this research team's comprehensive model is the first compelling case for reconnection as the main dissipation mechanism in a distant astrophysical system. The present work will study the bulk kinematics of relativistic reconnection outflows, the effects of plasma composition on reconnection outflows, and radiation processes in these self-same outflows. These will be the first kinetic simulations to model relativistic reconnection in an electron-ion plasma, and among the first to treat radiative losses self-consistently.The powerful research tool used here will be made freely available, with all necessary documentation, test problems, diagnostic tools, and sample scripts. The study itself applies widely not only to other astrophysical systems such as pulsar wind nebulae, gamma-ray bursts, and accretion disk coronae, but also to space physics applications and laboratory plasmas. One postdoctoral researcher will be supported, trained, and mentored in high-performance computing and the use of simulations.

Blazars是活跃的银河核的子集，它们是高能星系的岩心，它是因为它们的材料喷射以接近光线的速度流出的事实，恰好是安排的，以指向我们。因此，Blazars可以直接了解如何在快速移动的等离子体中辐射和降解能量。不幸的是，目前的解释证明不足。该研究团队推出了一种新模型，在初始，近似研究中看起来非常有前途。该项目将使用新的计算技术来模拟大量高速等离子体的运动，以详细研究问题，以通过与天文观测来区分可能的替代方案。为这项工作开发的研究工具将包装供其他人用于等离子体科学的许多领域。布拉萨尔是由地面和空间基观测器检测到的持续性外层次伽马射线辐射的主要来源。它们提供了相对论无碰撞等离子体中耗散和辐射过程的直接视图。最近对快速强烈耀斑的观察结果表明，发射区域非常紧凑，并且洛伦兹因子比无线电观测得出的散装射流值更高。使用局部相对论的子流（称为Minijets）的半分析模型，已重现了耀斑的大麻片的主要特征，但基于粗糙的近似值。该项目将使用新的，完全辐射的粒子中的粒子（PIC）代码来研究相对论等离子体中的无碰撞重新连接，包括等离子体磁化，磁导向场的强度和等离子体组成的效果，可以对散装等离子体运动，粒子加速度，粒子加速度和辐射签名具有。将模拟时间依赖性光谱与现有数据进行比较。令人困惑的伽玛射线燃烧的火焰不能归因于冲击加速度或任何其他磁性水力动力学过程，并且该研究团队的综合模型是重新连接的第一个令人信服的案例，作为遥远天体系统中的主要耗散机制。目前的工作将研究相对论重新连接外流的批量运动学，等离子体组成对重新连接流出的影响以及这些自称流出中的辐射过程。这些将是对电子等离子体中相对论重新连接建模的第一个动力学模拟，并且在第一个以自感是例的辐射损失的仿真中。此处使用的强大研究工具将免费提供，并提供所有必要的文档，测试问题，诊断工具和示例脚本。该研究本身不仅广泛适用于其他天体物理系统，例如脉冲星云，伽马射线爆发和增生盘冠状动脉，还适用于太空物理应用和实验室等离子体。一名博士后研究人员将在高性能计算和使用模拟方面得到支持，培训和指导。