In a stretch of the universe 6.5 billion light years away, astronomers have detected a young galaxy with a bizarrely strong magnetic field that is making them question the accepted theory of how galactic magnetic fields form. “This was a complete surprise,” said [lead researcher] Arthur Wolfe…. “The magnetic field we measured is at least an order of magnitude larger than the average value of the magnetic field detected in our own galaxy” [SPACE.com].
In the current dynamo theory of magnetic field formation, large galaxies develop strong magnetic fields through a slow and gradual process. Astrophysicists think these fields are slowly built up from smaller ‘seed fields’ that surround the charged particles blasted out by supernovae. Over billions of years, the galaxies’ slow spin whips up these particles and acts like a dynamo to align and amplify the fields [New Scientist].
This galaxy, known as DLA-3C286, is too young for that process to have already occurred. The findings, described in Nature [subscription required], have researchers searching for an alternate explanation for the magnetic field they observed. One possibility is that DLA-3C286 is not one galaxy but two caught in the act of colliding, said Wolfe. When galaxies collide their gases mix in ways that can generate much stronger magnetic fields — for a short time. Unfortunately, said Wolfe, the chance of catching galaxies in the act of colliding is about one in 100. So either his team got very lucky, or something else is going on [Discovery News].