The Cosmic InfraRed Background (CIRB) is the radiation from stars in
many faint galaxies. It is what is left over after emission from our
Solar System and our Galaxy has been subtracted away.
Here are pictures of the sky before and after
this foreground subtraction.
The near-infrared (wavelengths near 2-3 microns) and optical (wavelengths
near 500 nm) part of this extragalactic background light is just
starlight redshifted into the infrared.
But some starlight is absorbed
by dust and re-emitted in the far-infrared (wavelengths near 100
microns). The figure below shows the cosmic near-infrared background
in blue on the right, the cosmic far-infrared background in green in the
middle, and the cosmic microwave background on the left.
The black data points on this graph come from the DIRBE experiment on the COBE satellite. The red data points are modified DIRBE results that assume that 37.5% of the 100 micron radiation seen after extrapolating to zero neutral hydrogen column density is due to an error in the zodiacal light model used by Hauser et al.
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© 1999-2000 Edward L. Wright. Last modified 9-May-2000