Year: 2026
Type: preprint
Abstract: Magnetic fields are dynamically important across many astronomical environments, yet their origin, strength, and evolution over cosmic time remain poorly understood. Ordered magnetic fields are ubiquitous in the nearby Universe, as revealed by a range of observational techniques, but evidence for their existence at cosmological distances is scarce. Recent ALMA detections of polarised dust emission indicate that galactic-scale ordered magnetic fields, spanning up to kiloparsec scales, were already present in massive star-forming galaxies at redshifts up to $z\sim5.6$. This white paper argues that the ALMA2040 concept -- with its nearly tenfold improvement in sensitivity and angular resolution, and full-polarisation capability extended to higher-frequency bands -- will open up the study of cosmic magnetism in the early Universe. We identify four science drivers: constraining the dynamos that generate galactic-scale ordered fields, measuring the strength of early magnetic fields, connecting magnetic fields to galaxy evolution across cosmic time, and constraining dust grain properties through the polarised spectral energy distribution. We summarise the corresponding requirements in angular resolution, spectral coverage, and sensitivity, and discuss synergies with next-generation telescopes.
Source: arXiv (Cornell University)
Authors: Chen, Jianhang, Kaasinen, Melanie, Lopez-Rodriguez, Enrique, Vlemmings, Wouter, Lapi, Andrea, Paladino, Rosita, Stacey, Hannah, Cox, Pierre, Bakx, Tom J. L. C., Faisst, Andreas, Hodge, Jacqueline, da Cunha, Elisabete, Boogaard, Leindert A., Nguyen, Dieu D., Kumar, Adarsh, Wang, Leo, Popping, Gergö, de Roo, Willem, Vegetti, Simona
Institutions: Max Planck Institute for Extraterrestrial Physics, Australian National University, University of South Carolina, Chalmers University of Technology, Scuola Internazionale Superiore di Studi Avanzati, Centre National de la Recherche Scientifique, European Southern Observatory, Institut d'Astrophysique de Paris, Sorbonne Université, Université Pierre-et-Marie-Curie, California Institute of Technology, Infrared Processing and Analysis Center, Leiden University, Leiden Observatory, The University of Western Australia, International Centre for Radio Astronomy Research, University of Michigan, University of Atacama, Cornell University, Max Planck Institute for Astrophysics
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7222465119