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Young Galaxies Also Have Powerful Magnetic Fields

Magnetic fields seem to form relatively fast in galaxies

Jul 17, 2008 06:51 GMT  ·  By
Image of the M51 galaxy superimposed with the contour of the radio intensity and the direction of the magnetic field lines
   Image of the M51 galaxy superimposed with the contour of the radio intensity and the direction of the magnetic field lines

The general belief amongst astrophysicists is that the magnetic field of a galaxy evolves simultaneously with the galaxy, slowly building up in time. New observations of the distant universe on the other hand, appear to suggest that this is not quite true and that young galaxies also possess powerful magnetic fields that develop in the early stages of galaxy evolution.

"The magnetic fields in these galaxies were very strong, at least as strong as they are today, at a time when the age of the universe was only one third of its current age. That puts strong constraints on the evolution of magnetic fields," said Francesco Miniati of the Swiss Federal Institute of Technology.

Using ESO's Paranal Observatory located on Cerro Paranal, Chile, Miniati and his team were set to observe distant quasars in the optical and radio wavelengths of the electromagnetic spectrum. When the radio signatures coming from some quasars were analyzed, the research team discovered that part of them appeared to have passed through a magnetic field. Later investigations revealed that the magnetic signature was in fact coming from galaxies between the distant quasars and Earth.

"We were surprised that we could actually measure this so cleanly, and we were surprised that these galaxies had such strong magnetic fields early on. This has been suggested before, but seen convincingly only for some individual galaxies. What we were able to show with this measurement is that all regular galaxies early on have these kinds of strong magnetic fields," Miniati said.

Current models suggest that the magnetic field of a galaxy evolves from tiny seeds, such as a star or perhaps a quasar, and grows as gas inside the galaxy is stirred up by supernova explosions and the rotation of the galaxy. This in turn implies that the magnetic field cannot form rapidly, but builds up in time. The observations made by Miniati and his team suggest otherwise and could lead to the rethinking of the models regarding how a magnetic field is established inside a young galaxy.