Galactic Magnetism: Extended is the new Compact

银河磁力：扩展是新的紧凑型

• 批准号: RGPIN-2016-04538
• 负责人: Brown, JoAnne
• 金额: $ 1.97万
• 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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=681851
• 关键词: Galactic; Magnetism; Extended; new; Compact

Magnetic fields are one of the four primary components of the interstellar medium (ISM), or, 'the stuff between the stars'. The other components are gas, dust, and cosmic rays (highly energetic charged particles). Magnetic fields are believed to be important in galactic pressure balance, star formation, and perhaps even in the formation of galaxies themselves. Understanding the structure of magnetic fields within our Galaxy (and others) provides us with important constraints on models addressing how the Galactic magnetic field originally formed and how it is evolving. ***However, unlike the other constituents of the ISM, magnetic fields do not give off any form of light. Consequently, unless they are located in a region of space close enough to be measured in situ with a magnetometer (e.g., by spacecraft like Voyager 1 and 2), magnetic fields cannot be directly detected with any type of telescope. This makes determining the properties of magnetic fields more challenging than for the other ISM components.******Instead, we take advantage of the fact that magnetic fields can change the properties of light that is generated within their presence and they can affect light that passes through them, primarily through a process known as Faraday rotation.This process rotates the property of 'polarisation angle' of the incoming signal, and is dependent on the wavelength of the signal, as well as the magnetic field and electron density along the line-of-sight to the source. If we know something about the electron density, we can "work backwards" to determine what the magnetic field distribution must be to produce the rotation we measure. ***Most of what we currently know about the Galactic magnetic field has been determined using light from pulsars (exploded stars) and external galaxies as 'plumb-line' sources; the more sources we can look at, the more information we can piece together. Much like reconstructing an image from individual pixels, the goal has been to observe the Faraday rotation of as many sources as possible, at the highest density. From these data, we are piecing together the story of the Galactic magnetic field. ***However, many questions still remain. I believe the next big step forward in understanding Galactic magnetism will originate from studies using data from the 'extended emission'. Rather than looking at (polarised) light as it passes through the magnetic field of our Galaxy, we can use the (polarised) extended emission light that is being emitted from regions within the magnetic field. These data have the potential to bring all of the pieces of the Galactic magnetic field puzzle together. We are uniquely positioned in Canada to do this work, with the facilities and experience needed to address these questions. By doing this work, we will push back the boundaries of our knowledge of Galactic magnetism, and secure Canada's position as a world leader in the study of Cosmic magnetism.*** *** **

磁场是星际介质（ISM）或“恒星之间的物质”的四个主要组成部分之一。其他成分是气体、灰尘和宇宙射线（高能带电粒子）。磁场被认为对于星系压力平衡、恒星形成，甚至可能对于星系本身的形成都很重要。了解银河系（和其他银河系）内的磁场结构为我们提供了对解决银河系磁场最初如何形成及其演变的模型的重要约束。 ***然而，与 ISM 的其他成分不同，磁场不会发出任何形式的光。因此，除非它们位于足够近的空间区域，可以用磁力计（例如航海者 1 号和 2 号等航天器）进行现场测量，否则任何类型的望远镜都无法直接探测到磁场。这使得确定磁场的属性比其他 ISM 组件更具挑战性。******相反，我们利用这样一个事实，即磁场可以改变其存在范围内生成的光的属性，并且可以影响穿过磁场的光，主要通过称为法拉第旋转的过程。此过程旋转输入信号的“偏振角”属性，并且取决于信号的波长以及磁场和磁场。 沿源视线的电子密度。 如果我们对电子密度有所了解，我们就可以“逆向工作”来确定磁场分布必须如何才能产生我们测量的旋转。 ***我们目前对银河磁场的了解大部分都是通过使用来自脉冲星（爆炸恒星）和外部星系的光作为“铅垂线”源来确定的；我们可以查看的来源越多，我们可以拼凑的信息就越多。 就像从单个像素重建图像一样，目标是以最高密度观察尽可能多的源的法拉第旋转。 根据这些数据，我们正在拼凑出银河磁场的故事。 ***然而，许多问题仍然存在。 我相信理解银河磁性的下一个重大进步将源于使用“扩展发射”数据的研究。 我们可以使用从磁场内区域发射的（偏振）扩展发射光，而不是观察穿过银河系磁场的（偏振）光。 这些数据有可能将银河磁场谜题的所有部分整合在一起。我们在加拿大处于开展这项工作的独特地位，拥有解决这些问题所需的设施和经验。 通过这项工作，我们将突破银河磁学知识的界限，并确保加拿大在宇宙磁学研究方面的世界领先地位。*** *** **