Collaborative Research: A Comprehensive Theoretical Study of Cosmological Magnetic Fields and Turbulence: from the Early to Late Time Universe

不可见的磁场渗透到我们的宇宙各处，在不同的长度尺度上，从行星（如地球磁场）和恒星（如太阳磁场）到在星系（如银河系-我们银河系的磁场）和星系团中观测到的大尺度磁场，甚至在更大的尺度上填充星系团之间的空间。最近的观测数据表明，在空洞——最空旷、最黑暗的区域——也存在磁场。卡内基梅隆大学和麻省理工学院的科学家们提议开展一项理论研究计划，旨在了解宇宙磁性的起源，这是现代天体物理学中最具挑战性的问题之一，它影响着从地球周围的空间到宇宙遥远地区的尺度。作为该项目的一部分，这些pi将参与一系列的公共宣传活动，其节目旨在吸引当地的初高中学生和教师、残疾退伍军人以及公众。本研究项目的重点是研究宇宙磁场的起源、演化和观测结果，包括早期宇宙和星际介质中的物理过程。人们通常认为，观测到的宇宙磁场起源于来历不明的弱种子场。通常考虑两种基本情景：(1)自下而上（天体物理学）情景，其中种子通常非常弱，磁场从星系内部的局部源转移到更大的尺度；(2)一个自上而下的（宇宙学）场景，在早期宇宙的星系形成之前，在现在的大尺度上产生了一个强大的种子场。这个项目将研究自上而下的场景，以阐明磁场作为基础物理探针的作用。原始磁发生的物理学可以分为三个主要主题，在研究计划中加以解决：早期宇宙中磁场的产生，该磁场在不同宇宙时期受磁流体动力学效应影响的演变，以及通过一系列天体物理学和宇宙学观测对该磁场的探测。为了研究这些过程，该团队将执行连贯的理论和计算建模以及用于解释模拟和观测数据的统计分析。这项工作将提供区分不同磁发生情景所需的工具，并将确定观测到的宇宙磁场是否需要超越宇宙学和粒子物理学标准模型的物理学。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The invisible magnetic fields permeate our Universe everywhere, at different length scales ranging from planets (as Earth’s magnetic field) and stars (as Sun’s magnetic field) to the large-scale fields observed in galaxies (as the Milky Way – our Galaxy’s magnetic field) and galaxy clusters, and even at larger scales filling the space between galaxy clusters. Recent observational data suggest the existence of magnetic fields in voids – the emptiest and darkest regions – as well. Scientists at Carnegie Mellon University and the Massachusetts Institute of Technology propose to carry out a theoretical research program aimed at understanding the origin of cosmic magnetism, which is one of the most challenging questions in modern astrophysics that impacts scales from the space surrounding Earth to the faraway regions of the Universe. As part of this project, the PIs will participate in a series of public outreach activities, with programming designed to engage local middle and high school students and teachers, disabled veterans, as well as the general public.The focus of this research program is to investigate the origin, evolution and observational consequences of cosmic magnetic fields, including physical processes in the early-universe as well as in the interstellar medium. It is commonly assumed that the observed cosmic magnetic fields originated from the weak seed fields of unknown origin. Two basic scenarios are generally considered: (1) a bottom-up (astrophysical) scenario, where the seed is typically very weak and the magnetic field is transferred from local sources within galaxies to larger scales; (2) a top-down (cosmological) scenario, where a strong seed field is generated prior to galaxy formation in the early universe on scales that are now large. This project will investigate the top-down scenario in order to illuminate the role of magnetic fields as a probe of fundamental physics. The physics of primordial magnetogenesis can be broken down into three main motifs that are addressed in the research program: the generation of a magnetic field in the early universe, the evolution of this field subject to magnetohydrodynamic effects through the various cosmological epochs, and the detection of this magnetic field with a comprehensive array of astrophysical and cosmological observations. To study these processes, the team will perform coherent theoretical and computational modeling as well as statistical analysis used to interpret the simulations and observational data. This work will provide the tools needed to discriminate between different magnetogenesis scenarios, and will establish whether the observed cosmic magnetic fields require physics beyond the Standard Model of cosmology and particle physics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.