Young galaxy's magnetic field 10 times greater than average value in Milky Way

Washington, October 2 : Using a powerful radio telescope to peer into the early universe, a team of California astronomers has obtained the first direct measurement of a nascent galaxy's magnetic field as it appeared 6.5 billion years ago, which has revealed that it is at least 10 times greater than the average value in the Milky Way.

Astronomers believe the magnetic fields within our own Milky Way and other nearby galaxies-which control the rate of star formation and the dynamics of interstellar gas - arose from a slow "dynamo effect."

In this process, slowly rotating galaxies are thought to have generated magnetic fields that grew very gradually as they evolved over 5 billion to 10 billion years to their current levels.

But, astronomers have reported that the magnetic field they measured in this distant "protogalaxy" is at least 10 times greater than the average value in the Milky Way.

"This was a complete surprise," said Arthur Wolfe, a professor of physics at UC San Diego's Center for Astrophysics and Space Sciences who headed the team.

"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," he added.

The young protogalaxy that the astronomers probed, DLA-3C286, is located in a region of the northern sky that is directly overhead during the spring.

Until recently, astronomers knew very little about magnetic fields outside our own galaxy, having directly measured the magnetic field in only one nearby galaxy.

But, a team of Swiss and American astronomers reported an indirect measurement of the magnetic fields of 20 distant galaxies, using the bright light from quasars, which suggests that the magnetic fields of young galaxies were as strong when the universe was only a third of its current age as they are in the mature galaxies today.

According to Wolfe, "Our results present a challenge to the dynamo model, but they do not rule it out."

"Rather the strong field that we detect is in gas with little if no star formation, and an interesting implication is that the presence of the magnetic fields is an important reason why star formation is very weak in these types of protogalaxies," he added.

Wolfe said that his team has two other plausible explanations for what they observed.

"Our detection indicates that magnetic fields may be important factors in the evolution of galaxies, and in particular may be responsible for the low star formation rates detected throughout the gaseous progenitors of young galaxies in the early universe," he said.

ANI