Collaborative Research: Non-thermal Radio Halos of Spiral Galaxies as Clues to Galaxy Evolution

要了解像太阳这样的恒星和像地球这样的行星是如何形成的，我们必须了解银河系等星系是如何形成和演化的。这个项目是试图了解星际气体和高能粒子是如何从星系盘抛射出来的，而星系盘是发现大多数气体和恒星的地方，并与星系晕相互作用。这一循环过程对于理解星系中恒星形成的过程，以及星系形成时的生长速度很重要。这项研究使用了美国国家科学基金会资助的卡尔·G·詹斯基甚大阵列(VLA)和绿岸望远镜(GBT)的射电图像，来自阿帕奇点3.5米望远镜的光学数据，以及档案红外数据。该项目将为西班牙裔服务机构的两个博士论文提供机会，PI还将为国家射电天文台为小型大学教师运营的培训计划做出贡献。银河系的生长和演化取决于从银河系环境中获得气体和从盘中流出能量。需要了解这些过程的详细物理过程，而附近的边缘星系是最好的天体，在那里可以清楚地分离盘状和晕状成分。该项目利用了一项名为Chang-ES(邻近星系中的连续晕：EVLA调查)的关于边缘星系射电连续辐射的重大新调查。第一个目标是利用VLA和GBT制作的射电地图，通过评估非热气体压力梯度在星系晕中的作用，进一步加深我们对盘晕流动动力学的理解。第二个目标是确定宇宙射线(CR)注入和传播到星系晕的地点。为此，在结合红外数据和H-α图像使用Chang-ES图有力地分离热和非热射电发射之后，将绘制非热光谱指数的空间变化图。第三个科学目标是研究CR外流和热气体盘晕循环之间的联系，以及这种关系是否取决于恒星形成率等因素。

To understand how stars like the Sun and planets like Earth came to be, we must understand how galaxies, such as our Milky Way, form and evolve. This project is an attempt to understand how interstellar gas and energetic particles are ejected from galaxy disks, where most of the gas and stars are found, and interact with the galaxy halo. This cyclical process is important for understanding how star formation proceeds in galaxies, and the rate at which galaxies grew when they were forming. The study makes use of radio images from the NSF-funded Karl G. Jansky Very Large Array (VLA) and the Green Bank Telescope (GBT), optical data from the Apache Point 3.5-meter telescope, as well as archival infrared data. The project will provide opportunities for two PhD student theses at Hispanic Serving Institutions, and the PIs will also contribute to a training program run by the National Radio Astronomy Observatory for faculty at small colleges.Galaxy growth and evolution depend on both the acquisition of gas from the galaxy environment and energetic outflows from disks. The detailed physics of these processes needs to be understood, and nearby edge-on galaxies are the best objects where it is possible to cleanly separate disk and halo components. The project leverages a major new survey of radio continuum emission from edge-on galaxies called CHANG-ES (Continuum Halos in Nearby Galaxies: an EVLA Survey). The first goal is to further our understanding of the dynamics of disk-halo flows by assessing the role of non-thermal gas pressure gradients in galaxy halos, using radio maps made from the VLA and GBT. The second goal focuses on identifying sites of cosmic ray (CR) injection and propagation into galaxy halos. For this, the spatial variation of the non-thermal spectral index will be mapped, after robustly separating thermal and non-thermal radio emission using CHANG-ES maps in conjunction with infrared data and H-alpha images. The third science goal is to examine the connection between CR outflows and disk-halo cycling of thermal gas, and whether this relation depends on factors such as star formation rate.