The Role of Cosmic Magnetic Fields in Galaxy Evolution

宇宙磁场在星系演化中的作用

• 批准号: RGPIN-2014-04042
• 负责人: Stil, Jeroen
• 金额: $ 1.82万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633412
• 关键词: Role; Cosmic; Magnetic; Fields; Galaxy

The Role of Magnetic Fields in Galaxy FormationEarth's magnetic field protects our atmosphere from the onslaught of the solar wind: a stream of plasma flowing from the Sun through the Solar System. A disturbance in the Sun's magnetic field can trigger a massive ejection of matter into space that can cause power outages and disruption of GPS equipment and satellite communication when it interacts with the Earth's magnetic field. Recently, NASA's Voyager 1 space probe recorded a sudden change in magnetic field strength, but not direction, as it presumably entered interstellar space. Magnetic fields pervade the universe. In many astrophysical situations from small to very large, magnetic fields play a decisive part in the motion of matter in the cosmos. In return the structure of cosmic magnetic fields is intimately related to the motion of matter. Understanding magnetic fields is necessary to understand the formation of structure, and its subsequent evolution.In this proposal I outline a research program that investigates the physics of magnetic fields in relation to the formation and evolution of galaxies. This includes galaxy assembly by accretion of matter, but also the interaction between magnetic fields and matter inside galaxies, and activity in the centre of galaxies (Active Galactic Nucleus or AGN) that ejects vast amounts of energy in the form of beams of matter into intergalactic space. For the moment, we know very little with confidence about magnetic fields in galaxies. This is in part due to limitations in the predictive nature of dynamo theory that describes how large-scale magnetic fields can be amplified and sustained from motions in an astrophysical plasma. In part, our lack of understanding of cosmic magnetic fields is due to limitations in our ability to derive quantitative information from observations. The latter will make significant steps forward in the next decade because of recent developments in receiver technology, and the design of a new international facility for radio astronomy called the Square Kilometre Array (SKA). One of five key science goals for the SKA is to study the origin and evolution of cosmic magnetism, and another includes galaxy evolution and cosmology.For normal galaxies, I investigate the relation of the magnetic field to global properties such as the rate of star formation and dynamics of a galaxy. To this end, I lead surveys with the Effelsberg radio telescope and the Expanded Very Large Array (EVLA). On much smaller scales in our own Milky Way galaxy, I investigate the connection between the gas and the small-scale magnetic field. I lead the polarization side of a survey of part of the disk of the Milky Way (THOR), and an early science project of the GALFACTS survey with the Arecibo 300-m radio telescope. Through collaboration on deep surveys of small areas of the sky, we investigate the properties of distant galaxies and AGN-powered radio sources. The magnetic field properties of radio galaxies are also the subject of a statistical investigation using a technique called stacking, and another early science project with the GALFACTS survey.This work includes both observations with state of the art facilities and modeling of radio emission and magnetic fields. In support of development of future sky surveys with SKA and its path finders, I am also investigating new applications to extract information from broad-band observations of the polarization of radio waves, the principal source of information about cosmic magnetic fields. This will lead to a deeper understanding of the origin of magnetic fields in the cosmos, and their role in the formation of structure in the universe.

磁场在银河系中的磁场中的作用可以保护我们的大气免受太阳风的冲击：从太阳流过太阳系的等离子体流。太阳磁场中的干扰会触发物质大量弹射到太空中，这可能会导致停电，并在与地球磁场相互作用时造成电力停电和破坏卫星通信。最近，NASA的Voyager 1空间探针记录了磁场强度的突然变化，但没有方向变化，因为它大概进入了星际空间。磁场遍布宇宙。在许多从小到非常大的天体物理情况下，磁场在宇宙中物质运动中起着决定性作用。作为回报，宇宙磁场的结构与物质运动密切相关。了解磁场对于了解结构的形成及其随后的演化是必要的。在该提案中，I概述了一个研究计划，该计划研究了与星系的形成和演化有关的磁场物理学。这包括通过物质积聚的星系组装，以及星系内磁场与物质之间的相互作用，以及星系中心（活性银河核或AGN）的活性，这些活动以物质束形式弹出大量的能量，以射入质量范围内。空间。目前，我们对星系中的磁场充满信心地知道。这部分是由于发电机理论的预测性质的局限性，该理论描述了如何放大大规模磁场并从天体物理等离子体中的运动中持续。在某种程度上，我们对宇宙磁场的了解不足是由于我们从观察值中得出定量信息的能力的局限性。由于接收器技术的最新发展以及新的国际射电天文学设施的设计称为平方公里阵列（SKA），后者将在未来十年内迈出重要一步。 SKA的五个关键科学目标之一是研究宇宙磁性的起源和演变，另一个包括星系的演化和宇宙学。对于正常的星系，我研究了磁场与全球性能的关系，例如星形形成的速率和银河系的动力学。为此，我通过Effelsberg射程望远镜和扩展的非常大的阵列（EVLA）进行了调查。在我们自己的银河系中，我在较小的尺度上研究了气体与小规模磁场之间的联系。我领导了对银河系磁盘（Thor）的一部分调查的两极分化，以及通过Arecibo 300-M射电望远镜进行的Galfacts调查的早期科学项目。通过对天空小区域进行深入调查的合作，我们研究了遥远的星系和AGN驱动无线电来源的特性。射电星系的磁场特性也是使用称为堆叠技术的技术进行统计研究的主题，以及另一个带有Galfacts调查的早期科学项目。这项工作包括具有最先进的设施的观察以及无线电发射和磁场的建模。为了支持使用SKA及其路径发现器的未来天空调查的开发，我还研究了新的应用程序，以从无线电波的极化（有关宇宙磁场的主要信息来源）中提取信息。这将导致对宇宙中磁场的起源以及它们在宇宙中结构形成中的作用有更深入的了解。