Investigating the Radio Continuum - Star Formation Relation in Nearby Galaxies

研究射电连续体 - 附近星系中恒星形成的关系

• 批准号: 2277920
• 金额: --
• 依托单位: University of Hertfordshire
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2277920
• 关键词: Investigating; Radio; Continuum; Star; Formation

The Interstellar Medium (ISM) of star-forming galaxies is pervaded with cosmic ray electrons. They move at relativistic speeds and lose their energy in the form of synchrotron emission in the ever present magnetic field which is frozen in with the ISM. The recent, vast increase in sensitivity of radio interferometers now offers the prospect of using the radio continuum (RC) emission from normal star forming galaxies as a proxy for the spatially resolved star formation rate (SFR), virtually bypassing any of the extinction issues that plague optical/UV observations. Once properly calibrated, a non-thermal radio continuum - SFR relation will provide a robust, unbiased, extinction free tool for characterising the SFR in both the Local Universe and at high redshift. Moreover, detailed observations at multiple wavelengths across the radio part of the electromagnetic spectrum can be used to to improve our understanding of the physical origin of synchrotron emission and the various energy loss mechanisms involved. In this project, sensitive, multi wavelength, high-resolution observations using the VLA of a sample of 4 nearby spiral galaxies taken from the THINGS survey will be analysed. These VLA observations will be combined with ancillary data including H-alpha, 24um, and the FUV to separate the radio continuum emission into its thermal and non-thermal components and compare these to the SFR. These results will be used to calibrate the RC-SFR relation on a resolved basis on scales from 200 to 700 pc, explore the equipartition magnetic field properties of the galaxies, and the intrinsic scatter in the RC-SFR relation.

恒星形成星系的星际介质（ISM）中充满了宇宙射线电子。它们以相对论的速度运动，并以同步辐射的形式在一直存在的磁场中失去能量，该磁场被冻结在ISM中。最近，射电干涉仪的灵敏度大幅提高，现在提供了使用正常恒星形成星系的射电连续体（RC）发射作为空间分辨恒星形成速率（SFR）的代理的前景，实际上绕过了困扰光学/紫外观测的任何消光问题。一旦正确校准，非热射电连续体- SFR关系将提供一个强大的、无偏倚的、无消光的工具，用于表征局部宇宙和高红移的SFR。此外，在电磁波谱的无线电部分的多个波长上的详细观测可以用来提高我们对同步加速器发射的物理起源和所涉及的各种能量损失机制的理解。在这个项目中，将分析利用VLA对从THINGS调查中获得的4个附近螺旋星系样本的敏感、多波长、高分辨率观测结果。这些VLA观测将与包括H-alpha、24um和FUV在内的辅助数据相结合，将射电连续体发射分为热和非热组分，并将其与SFR进行比较。这些结果将用于在200 ~ 700pc尺度上标定RC-SFR关系，探索星系的均分磁场特性，以及RC-SFR关系中的本征散射。