Collaborative Research: Cosmic magnetic fields: Origin, Evolution, and Signatures

观测表明，星系的磁场成分在星系的很大一部分范围内是相干的，具有确定的场强和相干尺度。了解这些场的起源是现代天体物理学中更具挑战性的问题之一。目前有两幅图：一幅是自下而上（天体物理学）的，在较小的尺度上产生种子场；另一幅是自上而下（宇宙学）的，在现在较大的尺度上产生星系形成之前的种子场。本项目旨在回答几个相关问题：(i)磁场是如何以及何时产生的？（ii）在宇宙膨胀的过程中它是如何演化的？（iii）种子磁场的振幅和统计性质能否解释在大尺度结构中观测到的磁场的性质？（四）种子磁场能否通过宇宙学观测探测到？如果是这样，(v)对这样一个原初磁场的观测约束是什么？该跨学科项目分为以下相关部分：(1)根据现有数据确定星系间磁场极限；(2)研究宇宙大尺度相关磁场产生机制；(3)数值研究宇宙膨胀过程中磁场的演化；(4)数值研究星系形成过程中种子磁场的放大和动力学；(5)预测宇宙种子磁场的可观测特征。这个独特的专家团队将显著提高目前对宇宙磁场起源、演化、观测极限和预测特征的理解。该研究包括高能物理、数据分析和解释、磁流体动力学过程的数值模拟以及星系和早期结构形成方面的重要工作。也许最重要的是，有一个机会可以证明，观测需要一个宇宙磁场，而在粒子物理学标准模型的范围内，任何运行机制都无法产生这个磁场。教育方面包括本科生和研究生的培养。一项积极的教育和公众宣传计划涉及堪萨斯中北部天文学会，堪萨斯州立大学起源理解中心，西奥多罗斯福小学（曼哈顿，堪萨斯），匹兹堡大学阿勒格尼天文台，斯坦福大学的“飞溅！”为高中生举办的活动，以及匹兹堡州立大学的外展活动。而且，作为国际合作的一部分，初级PI将在佐治亚州的Abastumani天体物理天文台为本科生举办宇宙学教育课程。

AST-1109180/1109275/1108790Kahniashvili/Ratra/KosowskyObservations show that galaxies have magnetic fields with a component that is coherent over a large fraction of the galaxy, with defined field strength and coherence scale. Understanding the origin of these fields is one of the more challenging questions of modern astrophysics. There are currently two pictures: a bottom-up (astrophysical) one, generating the seed field on smaller scales, and a top-down (cosmological) version, generating the seed field prior to galaxy formation on scales that are now large. This project aims to answer several relevant questions: (i) How and when was the magnetic field generated? (ii) How does it evolve during the expansion of the universe? (iii) Can the amplitude and statistical properties of this seed magnetic field explain the properties of the observed magnetic fields in large-scale structures? (iv) Is the seed magnetic field detectable through cosmological observations? And if so, (v) what are the observational constraints on such a primordial magnetic field?The interdisciplinary project divides into the following related parts: (1) determining intergalactic magnetic field limits from currently available data; (2) studying cosmological large-scale correlated magnetic field generation mechanisms; (3) numerically studying the evolution of the magnetic field during the expansion of the universe; (4) numerically studying seed magnetic field amplification and dynamics during galaxy formation; and (5) predicting observable signatures of a cosmological seed magnetic field. This unique team of experts will significantly improve the current understanding of the origin, evolution, observational limits, and predicted signatures, of a cosmic magnetic field. The research includes important work in high energy physics, data analysis and interpretation, numerical simulation of magnetohydrodynamic processes, and galaxy and early structure formation. Perhaps most importantly, there is a chance to establish that observations demand a cosmological magnetic field that cannot be generated by any mechanism operating within the confines of the Standard Model of particle physics.The educational aspects include the training of undergraduate and graduate students. A vigorous education and public outreach program involves the North Central Kansas Astronomical Society, the KSU Center for the Understanding of Origins, Theodore Roosevelt Elementary School (Manhattan, Kansas), Allegheny Observatory at the University of Pittsburgh, the Stanford University 'Splash!' events for high school students, and Pittsburg State University outreach events. And, as part of an international collaboration, the primary PI will conduct cosmology education sessions for undergraduate students at Abastumani Astrophysical Observatory, Georgia.