Fluctuations in the Cosmic Infrared Background
This animation shows the anisotropies of the Cosmic Infrared Background (CIB), in four of the frequency channels probed by the High Frequency Instrument (HFI) on board Planck, over a patch of the sky of 26 square degrees, corresponding to about 130 times the area of the Full Moon.
The four frequencies probed are 857 GHz, 545 GHz, 353 GHz and 217 GHz, respectively.
The CIB anisotropies are clearly visible as a network of clumped structures and correspond to the distribution of dusty, star-forming galaxies on very large scales and throughout cosmic history. In fact, moving across the various frequencies probed by Planck's HFI, a different amount and extent of structure is observed: this is a consequence of the fact that each frequency channel is most sensitive to the emission coming from galaxies at a certain redshift.
Observations at the highest frequency, corresponding to 857 GHz, yield most information about galaxies up to z~1, whereas the lower frequencies offer a chance to peer farther and farther away, out to z~1–4, thus emphasising Planck's ability to track down the early phases of galaxy formation.
The patch of the sky shown in this animation is located at a relatively high galactic latitude, where the foreground contamination due to the Milky Way's diffuse emission is less dramatic.