Images produced by the Planck satellite have revealed an enormous cloud of electrons traveling near the speed of light in the heart of our Galaxy, the Milky Way. These electrons interact with the Galaxy's magnetic field to produce a haze of microwave radiation seen by Planck.
The discovery builds upon earlier research by Planck team member Gregory Dobler, a postdoctoral fellow at the Kavli Institute for Theoretical Physics at UC Santa Barbara. Dobler, along with collaborators, previously studied hints of this emission in images from the Wilkinson Microwave Anistropy Probe, and led the initial discovery of a gamma-ray counterpart in data from the Fermi Gamma-Ray Space Telescope, originally termed the Fermi "haze" and later the Fermi "bubbles."
Several explanations have been proposed for this unusual behavior. "Theories include higher numbers of supernovae, galactic winds and even the annihilation of dark-matter particles," said Greg Dobler, a Planck collaborator from the University of California in Santa Barbara, Calif. Dark matter makes up about a quarter of our universe, but scientists don't know exactly what it is.
The Planck results will be announced this week in Bologna, Italy, at a conference devoted to Planck science. They also will be submitted to the Astronomy and Astrophysics Journal.