2023-09-11 04:00:03
Thanks to ALMA (Atacama Large Millimeter/submillimeter Array), astronomers have detected the magnetic field of a galaxy so distant that its light took more than 11 billion years to reach us: we see it as it was when the Universe was only 2.5 billion years old. This result provides astronomers with essential clues about the origin of the magnetic fields of galaxies such as ours. Milky Way. The 9io9 galaxy seen by ALMA
Many astronomical bodies in the Universe have magnetic fields, whether planets, stars or galaxies. “Many people may not know that our entire galaxy and other galaxies are crossed by magnetic fields that extend tens of thousands of light years,” says James Geach, professor of astrophysics at L’universitĂ© from Hertfordshire, UK, and lead author of the study published today in the journal Nature.
Enrique Lopez Rodriguez, a researcher at Stanford University (United States), who also participated in the study, adds: “We know very little about how these fields form, although they play a fundamental role in the evolution of galaxies. It is actually not known exactly at what point in the life of the Universe and how quickly magnetic fields in galaxies form, because until now astronomers have only mapped magnetic fields in nearby galaxies from U.S.
Today, thanks to ALMA, of which the European Southern Observatory (ESO) is a partner, James Geach and his team have discovered a magnetic field entirely formed in a distant galaxy, whose structure is similar to that observed in nearby galaxies. This field is approximately 1000 times weaker than the earth’s magnetic fieldbut it extends over 16,000 light years.
“This discovery gives us new clues about the formation of magnetic fields on a galactic scale,” explains James Geach. The observation of a fully developed magnetic field this early in the history of the Universe indicates that magnetic fields spanning entire galaxies can form quickly while young galaxies are still growing.
Infrared view of galaxy 9io9
The team believes that intense star formation in the early Universe may have played a role in accelerating the development of the fields. Furthermore, these fields can in turn influence how subsequent generations of stars form. Rob Ivison, co-author and astronomer at ESO, explains that this discovery opens “a new window on the internal workings of galaxies, because magnetic fields are linked to the matter which forms the new stars.
To achieve this detection, the team looked for light emitted by dust grains in the distant galaxy 9io9 (1). Galaxies are full of dust grains, and in the presence of a magnetic field, the grains tend to align and the light they emit becomes polarized. This means that light waves oscillate along a preferred direction rather than randomly. When ALMA detected and mapped a 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 achieved this,” says James Geach. The hope is that with this and subsequent observations of distant magnetic fields, the mystery of how these fundamental galactic components formed will begin to unravel.
Note:
(1) 9io9 was discovered as part of a citizen science project. The discovery was aided by viewers of the BBC’s British show Stargazing Live, who, over three nights in 2014, were invited to examine millions of images in search of distant galaxies.
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