Magnetic fields forever: LANL astophysicist battles a mystery

-A A +A
By Roger Snodgrass

A distinguished colleague, Stirling Colgate, once called him “Mr. Magnetic Fields in the Universe,” and Philip Kronberg continues to live up to that reputation.

Monday, Los Alamos National Laboratory announced Kronberg’s participation in a newly published paper that has turned around another theory about magnetic fields.

The findings, published as a letter in the journal Nature July 17, strengthen the idea that galactic magnetic fields have not grown up over billions of years, as some have thought, but were there from an early age.

A paper co-authored by Kronberg in 2004, in the Journal of the Korean Astronomical Society notes that cosmic magnetic fields – beyond localized phenomena associated with individual stars – were predicted nearly 60 years ago, and then confirmed in 1989.

Last year, Kronberg was part of a team using the Arecibo Observatory in Puerto Rico that found a cloud of high-energy plasma 300 million light years away. The enormous object, 80 times wider than the Milky Way, is known as Region A, and is thought to be a vast repository of magnetized material that streamed out on jets emerging from black holes.

At a conference of the American Physical Society’s Division of Plasma Physics last November, Kronberg discussed the importance of structures like Region A in magnetizing the galactic medium and its effects on the evolution of the universe. The phenomenon may also serve as an accelerator that launches ultra-high energy particles known as cosmic rays, some of which strike the Earth from time-to-time.

Earlier this year, Kronberg and associates refined their views of magnetic fields in the “high red-shift,” universe, going back 8 or 9 billion years, 4-5 billion years after the Big Bang.

“It was thought that, looking back in the past, earlier galaxies would not have generated much magnetic field,” Kronberg said in the LANL announcement. “The results of this study show that the magnetic fields within Milky Way-like galaxies have been every bit as strong over the last two-thirds of the universe’s age as they are now and possibly even stronger then.”

The recent research, was bolstered by optical evidence from the European Southern Observatory in Chile as interpreted by Martin Bernet, Francesco Miniati and Simon Lilly of the Swiss Federal Institute of Technology (ETH Zurich).

The scientific letter in Nature provides evidence contrary to the “dynamo theory,” for the origins of galactic magnetic fields, according to an announcement by ETH. The dynamo theory had argued that mechanical energy ginned up over long periods of time in spinning planets, stars and galaxies created weak magnetic fields that grew stronger over time.

The research “also serves as an important reminder of the potential importance of magnetic fields,” the Nature letter concludes, “which is usually completely ignored, in the formation and evolution of cosmic structures,” in the early period of the universe.

In 1990, Kronberg won the Alexander von Humboldt Award. He came to the laboratory from the University of Toronto in 2002. Earlier this year, he received the 2008 von Humboldt Award for his impact on astrophysics and radio astronomy. The award was given in Berlin on June 24. Kronberg is traveling in Europe through next month.