Investigating the Radio Continuum - Star Formation Relation in Nearby Galaxies

恒星形成星系的星际介质（ISM）中充满了宇宙射线电子。它们以相对论速度运动，并以同步辐射的形式在与ISM冻结在一起的始终存在的磁场中失去能量。最近，无线电干涉仪的灵敏度大幅提高，现在提供了前景使用无线电连续（RC）的正常星星形成星系的发射作为空间分辨星星形成率（SFR）的代理，几乎绕过任何灭绝的问题，困扰光学/紫外观测。一旦正确校准，非热射电连续谱- SFR关系将提供一个鲁棒的，无偏的，无消光的工具，用于表征本地宇宙和高红移的SFR。此外，在电磁波谱的无线电部分的多个波长处的详细观测可以用于提高我们对同步辐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，将分析从THINGS巡天中获得的4个邻近螺旋星系样本的VLA敏感、多波长、高分辨率观测。这些VLA观测将与包括H-α、24 μ m和FUV在内的辅助数据相结合，以将无线电连续辐射分为热和非热分量，并将其与SFR进行比较。这些结果将被用来校准的RC-SFR关系上解决的基础上从200至700 pc的尺度，探索星系的均分磁场的性质，和内禀散射的RC-SFR关系。

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.