Most distant galactic magnetic field yet, in galaxy 9io9
Earth has a magnetic field. Our sun has a magnetic field. Our Milky Way galaxy has a magnetic field. And other galaxies have magnetic fields, too. On September 6, 2023, astronomers using the ALMA telescope in the Atacama Desert in Chile said they’ve detected the most distant galactic magnetic field so far. The galaxy is called by the super-cool name of 9io9. Its light has to travel travel more than 11 billion years to reach us, from a time when the universe was a young 2.5 billion years old.
You can see 9io9’s magnetic field in the new image at top. It appears as a partial bluish arc with bright spots.
The journal Nature will publish these scientists’ research paper. Until then, you can access the preprint on the European Southern Observatory’s website.
Galaxies have magnetic fields, too
As lead author James Geach, an astrophysicist at the University of Hertfordshire, U.K., noted, it may not be common knowledge that galaxies have magnetic fields. And they are huge. He said:
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.
And even though astronomers know about galactic magnetic fields, there is still a lot to learn. Co-author Enrique Lopez Rodriguez, a researcher at Stanford University, added:
We actually know very little about how these fields form, despite their being quite fundamental to how galaxies evolve.
Galactic magnetic field is the farthest ever detected
Part of the reason for not fully understanding how galactic magnetic fields form is due to distance and the difficulty in observing them. So far, astronomers have mostly studied magnetic fields in galaxies that are closer to us. But to find out how these magnetic fields originally form; astronomers need to see ones that are much older and consequently farther away from us. This is where ALMA comes in.
Using this powerful radio telescope, the researchers found a magnetic field in a galaxy much more distant than any they’ve previously seen. It appeared to be similar to the magnetic fields in galaxies closer to us. And it’s not only distant, it’s immense, extending over 16,000 light-years across. Wow! Despite its size, however, a galaxy’s magnetic field is weak. This one is about 1,000 times weaker than Earth’s own magnetic field. So, as the saying goes, size isn’t everything.
You can “zoom in” to galaxy 9io9 in the video below:
As for the galaxy itself, viewers of the British BBC television program Stargazing Live found galaxy 9io9 as part of a citizen science project. They hunted distant galaxies in millions of scientific images over three nights in 2014, a work that located target galaxies for astronomers to study further.
Using galactic dust grains to find the magnetic field
The research team detected the galaxy’s magnetic field by examining light emitted by dust grains in the galaxy. Just as atoms in ferromagnetic materials will “line up” together when influenced by a magnetic field, dust grains in galaxies will align in the presence of a magnetic field. The dust grains then emit polarized light. That light is distinct from other light sources because it oscillates in only one direction. So if a galaxy is emitting this kind of polarized light, that is evidence for a galactic magnetic field.
How does a galaxy’s magnetic field form?
Since the host galaxy of this magnetic field is so far away and old, the discovery can provide information as to how such magnetic fields develop. Geach said:
This discovery gives us new clues as to how galactic-scale magnetic fields are formed.
The paper also states:
Magnetic fields are fundamental to the evolution of galaxies, playing a key role in the astrophysics of the interstellar medium (ISM) and star formation. Large-scale ordered magnetic fields have been mapped in the Milky Way and nearby galaxies, but it is not known how early in the universe such structures form.
Stars and magnetic fields in galaxies affect each other
One takeaway is that the magnetic fields seem to form quite quickly. This is based on the fact that the magnetic field already is fully formed in a very early period in the history of the universe (and its galaxy). So, how do these magnetic fields develop so fast? The researchers said it has to do with intense star formation. This happened early on, when the universe was still quite young. And what goes around, comes around. The newly formed magnetic fields, in turn, then influence future star formation. As co-author Rob Ivison at ESO noted, the discovery:
… opens a new window onto the inner workings of galaxies, because the magnetic fields are linked to the material that is forming new stars.
These results will provide scientists with new insights not only about how magnetic fields form and function on scales immensely larger than those anywhere in our solar system, but also how they affected the evolution of galaxies in the early universe. From when we played with magnets as children to galactic “magnets” spanning thousands of light-years, it’s a new cosmic look at a common natural phenomenon.
Bottom line: Astronomers using the ALMA telescope have detected the most distant galactic magnetic field that scientists have yet seen. It existed when the universe was only 20% of its current age.
Source: Polarized thermal emission from dust in a galaxy at red-shift 2.6
Read more: Galaxies have magnetic fields, too! Images here
Read more: Milky Way center: Threads of hot gas and magnetic fields
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