Using precise full-sky observations from Planck , and applying several methods of component separation , we identify and characterize the emission from the Galactic “ haze ” at microwave wavelengths .
The haze is a distinct component of diffuse Galactic emission , roughly centered on the Galactic centre , and extends to |b| \sim 35 \degr in Galactic latitude and |l| \sim 15 \degr in longitude .
By combining the Planck data with observations from the Wilkinson Microwave Anisotropy Probe we are able to determine the spectrum of this emission to high accuracy , unhindered by the large systematic biases present in previous analyses .
The derived spectrum is consistent with power-law emission with a spectral index of -2.55 \pm 0.05 , thus excluding free-free emission as the source and instead favouring hard-spectrum synchrotron radiation from an electron population with a spectrum ( number density per energy ) dN / dE \propto E ^ { -2.1 } .
At Galactic latitudes |b| < 30 \degr , the microwave haze morphology is consistent with that of the Fermi gamma-ray “ haze ” or “ bubbles , ” indicating that we have a multi-wavelength view of a distinct component of our Galaxy .
Given both the very hard spectrum and the extended nature of the emission , it is highly unlikely that the haze electrons result from supernova shocks in the Galactic disk .
Instead , a new mechanism for cosmic-ray acceleration in the centre of our Galaxy is implied .