Farthest Ever: Galaxy’s Magnetic Field Detected From 11 Billion Light-Years Away

Astronomers have discovered an ancient galaxy’s magnetic field, shedding light on the early universe’s cosmic evolution and star formation processes.

Using the Atacama Large Millimeter/submillimeter Array (ALMAThe Atacama Large Millimeter/submillimeter Array (ALMA) is the largest ground-based facility for observations in the millimeter/submillimeter regime in the world. ALMA comprises 66 high-precision dish antennas of measuring either 12 meters across or 7 meters across and spread over distances of up to 16 kilometers. It is an international partnership between Europe, the United States, Japan, and the Republic of Chile.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>ALMA), astronomers have detected the magnetic field of a galaxy so far away that its light has taken more than 11 billion years to reach us: we see it as it was when the Universe was just 2.5 billion years old. The result provides astronomers with vital clues about how the magnetic fields of galaxies like our own Milky WayThe Milky Way is the galaxy that contains our Solar System and is part of the Local Group of galaxies. It is a barred spiral galaxy that contains an estimated 100-400 billion stars and has a diameter between 150,000 and 200,000 light-years. The name "Milky Way" comes from the appearance of the galaxy from Earth as a faint band of light that stretches across the night sky, resembling spilled milk.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>Milky Way came to be.

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Using ALMA, astronomers have detected the magnetic field of a galaxy so far away that its light has taken more than 11 billion years to reach us. Never before had we detected a galaxy’s magnetic field this far away. This video summarizes the discovery. Credit: ESOCreated in 1962, the European Southern Observatory (ESO), is a 16-nation intergovernmental research organization for ground-based astronomy. Its formal name is the European Organization for Astronomical Research in the Southern Hemisphere.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>ESO

Magnetic Fields Across the Universe

Lots of astronomical bodies in the Universe have magnetic fields, whether it be planets, stars, or galaxies. “Many people might not be aware that our entire galaxy and other galaxies are laced with magnetic fields, spanning tens of thousands of light-years,” says James Geach, a professor of astrophysics at the University of Hertfordshire, UK, and lead author of the study published recently in the scientific journal Nature.

“We actually know very little about how these fields form, despite their being quite fundamental to how galaxies evolve,” adds Enrique Lopez Rodriguez, a researcher at Stanford University, USA, who also participated in the study. It is not clear how early in the lifetime of the Universe, and how quickly, magnetic fields in galaxies form because so far astronomers have only mapped magnetic fields in galaxies close to us.

This infrared image shows the distant galaxy 9io9, seen here as a reddish arc curved around a bright nearby galaxy. This nearby galaxy acts as a gravitational lens: its mass curves spacetime around it, bending lightrays coming from 9io9 in the background, hence its distorted shape. This color view results from combining infrared images taken with ESO’s Visible and Infrared Survey Telescope for Astronomy (VISTA) in Chile and the Canada France Hawaii Telescope (CFHT) in the US. Credit: ESO/J. Geach et al.

The Role of Star Formation and Future Research

Now, using ALMA, in which the European Southern Observatory (ESO) is a partner, Geach and his team have discovered a fully formed magnetic field in a distant galaxy, similar in structure to what is observed in nearby galaxies. The field is about 1000 times weaker than the Earth’s magnetic field, but extends over more than 16,000 light-years.

“This discovery gives us new clues as to how galactic-scale magnetic fields are formed,” explains Geach. Observing a fully developed magnetic field this early in the history of the Universe indicates that magnetic fields spanning entire galaxies can form rapidly while young galaxies are still growing.

The team believes that intense star formation in the early Universe could have played a role in accelerating the development of the fields. Moreover, these fields can in turn influence how later generations of stars will form. Co-author and ESO astronomer Rob Ivison says that the discovery opens up “a new window onto the inner workings of galaxies, because the magnetic fields are linked to the material that is forming new stars.”

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This video takes us on a journey from our home in the Milky Way to a galaxy far, far away, 9io9. We first see the night sky in visible light, and then switch to infrared light when we finally reach 9io9. Here, the galaxy appears as a faint reddish arc curved around a bright nearby galaxy. We then see the ALMA image of 9io9 at millimeter wavelengths, with the orientation of the magnetic field indicated by overlaid curves. Credit: ESO/ALMA (ESO/NAOJ/NRAO)/DESIThe Dark Energy Spectroscopic Instrument (DESI) is a new instrument for conducting a spectrographic survey of distant galaxies that has been retrofitted onto the Mayall Telescope on top of Kitt Peak in the Sonoran Desert 55 miles distant from Tucson, Arizona. Its main components are a focal plane containing 5000 fiber-positioning robots and a bank of spectrographs which are fed by the fibers. It enables an experiment to probe the expansion history of the Universe and the mysterious physics of dark energy.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>DESI/CFHT/N. Risinger (skysurvey.org)/J. Geach et al.

Techniques for Detecting Distant Magnetic Fields

To make this detection, the team searched for light emitted by dust grains in a distant galaxy, 9io9.^[1] Galaxies are packed full of dust grains and when a magnetic field is present, the grains tend to align and the light they emit becomes polarized. This means that the light waves oscillate along a preferred direction rather than randomly. When ALMA detected and mapped a polarized signal coming from 9io9, the presence of a magnetic field in a very distant galaxy was confirmed for the first time.

“No other telescope could have achieved this,” says Geach. The hope is that with this and future observations of distant magnetic fields the mystery of how these fundamental galactic features form will begin to unravel.

Reference: “Polarized thermal emission from dust in a galaxy at redshift 2.6” by J. E. Geach, E. Lopez-Rodriguez, M. J. Doherty, Jianhang Chen, R. J. Ivison, G. J. Bendo, S. Dye and K. E. K. Coppin, 6 September 2023, Nature.
DOI: 10.1038/s41586-023-06346-4

Notes

1. 9io9 was discovered in the course of a citizen science project. The discovery was helped by viewers of the British BBC television program Stargazing Live, when over three nights in 2014 the audience was asked to examine millions of images in the hunt for distant galaxies.

The research team is composed of J. E. Geach (Centre for Astrophysics Research, School of Physics, Engineering and Computer Science, University of Hertfordshire, UK [Hertfordshire]), E. Lopez-Rodriguez (Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, USA), M. J. Doherty (Hertfordshire), Jianhang Chen (European Southern Observatory, Garching, Germany [ESO]), R. J. Ivison (ESO), G. J. Bendo (UK ALMA Regional Centre Node, Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University of Manchester, UK), S. Dye (School of Physics and Astronomy, University of NottinghamThe University of Nottingham is a public research university located in Nottingham, England. It was founded in 1881 and is one of the oldest and most prestigious universities in the country. The University of Nottingham has a wide range of academic programs and disciplines, including the humanities, social sciences, natural sciences, engineering, and medicine. It is known for its strong research and has a number of research centers and institutes focused on various fields, including environmental science, energy, and health. It is a member of the Russell Group, a group of leading research-intensive universities in the UK.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>University of Nottingham, UK) and K. E. K. Coppin (Hertfordshire).