VLA Reveals Distant Galaxy’s Magnetic Field

“The difference tells us that this galaxy has a large-scale, coherent magnetic field, similar to those we see in nearby galaxies in the present-day universe,” Mao said. The similarity is both in the strength of the field and in its arrangement, with magnetic field lines twisted in spirals around the galaxy’s rotation axis.

Since this galaxy is seen as it was almost five billion years ago, when the universe was about two-thirds of its current age, this discovery provides an important clue about how galactic magnetic fields are formed and evolve over time.

“The results of our study support the idea that galaxy magnetic fields are generated by a rotating dynamo effect, similar to the process that produces the Sun’s magnetic field,” Mao said. “However, there are other processes that might be producing the magnetic fields. To determine which process is at work, we need to go still farther back in time — to more distant galaxies — and make similar measurements of their magnetic fields,” she added.

“This measurement provided the most stringent tests to date of how dynamos operate in galaxies,” said Ellen Zweibel from the University of Wisconsin-Madison.

Magnetic fields play a pivotal role in the physics of the tenuous gas that permeates the space between stars in a galaxy. Understanding how those fields originate and develop over time can provide astronomers with important clues about the evolution of the galaxies themselves.

Mao and her colleagues are reporting their results in the journal Nature Astronomy.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Contacts and sources:
Dave Finley