Using the Atacama Large Millimeter/Submillimeter Array (ALMA), astronomers have discovered the magnetic field of a galaxy so far away that its light takes more than 11 billion years to reach us: We see the universe as it was when it was only 2.5 billion years old. years old. The result gives astronomers vital clues to how the magnetic fields of galaxies like the Milky Way form.

Many astronomical objects in the universe, whether planets, stars, or galaxies, have magnetic fields. “Many may not know that our entire galaxy and other galaxies are filled with magnetic fields spanning tens of thousands of light-years,” said James Geach, lead author of the study and professor of astrophysics at the University of Hertfordshire. , published today Nature.

“Although they are fundamental to the evolution of galaxies, we actually know very little about how these fields formed,” adds researcher Enrique López Rodríguez of Stanford University in the US, who participated in the study. It is not clear at what stage the life of the universe is and how fast magnetic fields are forming in galaxies, because so far astronomers have only mapped magnetic fields in galaxies close to us.

Now using ALMA, run in partnership with the European Southern Observatory (ESO), Gich and his team have discovered a fully formed magnetic field in a distant galaxy, similar in structure to that observed in nearby galaxies. The field is about 1,000 times weaker than Earth’s magnetic field, but spans over 16,000 light-years.

“This discovery gives us new clues about how magnetic fields form on the galactic scale,” explains Gich. The observation of a fully developed magnetic field so early in the universe’s history suggests that magnetic fields that span entire galaxies can form rapidly while young galaxies are still growing.

The team believes that intense star formation in the early universe may have played a role in accelerating the development of the fields. These fields may also influence the formation of later star generations. Co-author and ESO astronomer Rob Ivison says the discovery “opens a new window into the inner workings of galaxies, as magnetic fields are linked to material that forms new stars.”

To make this discovery, the team looked for light emitted by dust particles in the distant galaxy 9io9. Galaxies are full of dust particles, and when a magnetic field is present, the particles tend to align and the light they emit becomes polarized. This means that the light waves oscillate in the desired direction, not randomly. When ALMA detected and displayed the polarized signal from 9io9, the presence of a magnetic field in a very distant galaxy was confirmed for the first time.

“No other telescope could have accomplished this,” says Geach. It is hoped that with these and future observations of distant magnetic fields, the mystery of how these fundamental galactic features are formed will begin to unravel. Source