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

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

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.