Astronomers have made the first detection in another galaxy of a magnetic field that extends out into the galaxy’s halo.
The image above, based on data from the Jansky radio telescope, illustrates what they found..
The spiral galaxy is seen edge-on, with its disk of stars shown in pink. The filaments, shown in green and blue, extend beyond the disk into the galaxy’s extended halo. Green indicates filaments with their magnetic field pointing roughly toward us and blue with the field pointing away. This phenomenon, with the field alternating in direction, has never before been seen in the halo of a galaxy.
“This is the first time that we have clearly detected what astronomers call large-scale, coherent, magnetic fields far in the halo of a spiral galaxy, with the field lines aligned in the same direction over distances of a thousand light-years. We even see a regular pattern of this organized field changing direction,” said Marita Krause, of the Max-Planck Institute for Radioastronomy in Bonn, Germany.
The galaxy, dubbed the Whale by the astronomers, is about 35 million light years away, and has a diameter of about 80,000 light years, slightly smaller than the Milky Way.