Galaxy Evolution and Environment -- Disk-Halo Outflows, Feedback and Magnetic Fields

星系演化与环境——盘晕流出、反馈和磁场

• 批准号: RGPIN-2016-03617
• 负责人: Irwin, Judith
• 金额: $ 1.6万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=654315
• 关键词: Galaxy; Evolution; Environment; Disk; Halo

My program involves a study of outflows from spiral galaxies and their effect on galaxy formation and evolution. Current models require strong outflows (called 'feedback') in order to form the galaxies that we see today. But the details of feedback mechanisms are not well known and current computer simulations must include assumptions about feedback which are reasonable, but not verified through observation. Fortunately, we now know that nearby fully formed galaxies also experience outflows that are lower in power yet similar in nature to those that occurred at a time when galaxies first formed. Nearby galaxies, not only are fully formed versions of their infant counterparts, but also represent local laboratories within which outflows can be studied in great detail. With careful scrutiny, we can identify and quantify the important physics, dynamics, causes and effects of this important activity. In this Discovery Grant (DG) cycle, I will primarily focus on radio continuum emission from the interaction between cosmic rays and magnetic fields.****The consequences of outflows are substantial. Significant gas is expelled from the disk leading to modifications in the galaxy's evolution (e.g. adjusted star formation rates, re-distribution of chemical elements, altered magnetic field structures). There are important implications both locally (such as around our own Sun) and globally across a galaxy. For example, our Sun exists in a 'local hot bubble' which is believed to have been excavated by previous supernova activity. Could this have affected the formation and evolution of our Sun and, by implication, the Earth itself? Indeed the Galactic `habitable zone' will certainly be affected by outflows. ****My first goal is to complete the full data release of CHANG-ES (Continuum Halos in Nearby Galaxies -- an EVLA Survey), an international consortium of which I am principal investigator. We have used the EVLA (Expanded Very Large Array) radio telescope, whose correlator was built in Canada, to observe 35 edge-on galaxies in a variety of telescope configurations, at an opportunistic time prior to the future Square Kilometre Array. Our 405 hours of EVLA data constitute 175 data sets which include, for the first time, information on the magnetic field direction in edge-on galaxies. Green Bank Telescope time has also been awarded.****Canada, via CHANG-ES, has become a center of excellence in high quality training for processing interferometric data sets and dealing with `big data'. Our first legacy-value public data release occurred in August/2015 and there will be two more over the time period of this DG. Our own consortium is making new discoveries from these data (see text). With the public data release, other scientists will also benefit from the results, leveraging our own work. Our group's focus has shifted more and more towards the science, and we anticipate many more answers (and surprises) in the future.****

我的计划涉及研究螺旋星系的流出及其对星系形成和进化的影响。当前的模型需要强大的外流（称为“反馈”），以形成我们今天看到的星系。 但是，反馈机制的细节尚不清楚，当前的计算机模拟必须包括有关反馈的假设，这些假设是合理的，但不能通过观察验证。 幸运的是，我们现在知道，附近的完全形成的星系也经历了较低的动力流出，但性质上与在星系首次形成时发生的流出相似。 附近的星系，不仅是其婴儿对应物的完全形成版本，而且代表了当地实验室，可以在其中详细研究流出。经过仔细的审查，我们可以识别和量化这一重要活动的重要物理，动力学，原因和影响。在这个发现赠款（DG）周期中，我将主要关注宇宙射线与磁场之间相互作用的无线电连续体发射。****流出的后果是很大的。 从磁盘中排出明显的气体，导致星系演变的改变（例如，调整后的恒星形成速率，重新分布化学元件，改变磁场结构）。在当地（例如在我们自己的太阳周围）和全球范围内都有重要的含义。 例如，我们的太阳存在于“当地热泡沫”中，据信这是由以前的超新星活动挖掘出来的。 这会影响我们的太阳的形成和演变，并暗示地球本身吗？实际上，银河的“可居住区”肯定会受到流出的影响。 ****我的第一个目标是完成Chang-es（附近星系中的连续晕晕 - EVLA调查）的完整数据发布，这是我的国际财团。 我们已经使用了在加拿大建造的EVLA（扩展的非常大的阵列）射电望远镜，该望远镜在未来的平方公里阵列之前的机会主义时间观察了各种望远镜配置的35个边缘星系。我们的405小时EVLA数据构成了175个数据集，其中首次包括有关边缘星系中磁场方向的信息。 绿色银行望远镜时间也已被授予。 我们的第一个旧版公共数据发布发生在2015年8月/2015年，在此DG的期间将有两个。 我们自己的财团正在从这些数据中获得新发现（请参阅文本）。 随着公共数据发布，其他科学家还将从结果中受益，利用我们自己的工作。我们小组的重点越来越多地转移到科学上，我们预计将来会有更多的答案（和惊喜）。****