The Spectrum of the Extragalactic Far‐Infrared Background from theCOBEFIRAS Observations

The COBE FIRAS data contain foreground emission from interplanetary, Galactic interstellar dust and extragalactic background emission. We use three di erent methods to separate the various emission components, and derive the spectrum of the extragalactic far-infrared background (FIRB). Each method relies on a di erent set of assumptions, which a ect the FIRB spectrum in di erent ways. Despite this, the FIRB spectra derived by these di erent methods are remarkably similar. The average spectrum that we derive in the l \ 580 cm~1 (2000125 km) frequency interval is I (l) \ (1. 3 ⁰. 4) K), where cm~1 km), and P is the Planck function. ] 10~5 (l/l 0) 0. 64B0. 12P l (18. 5 ¹. 2 l 0 \ 100 (j 0 \ 100 The derived FIRB spectrum is consistent with the (DIRBE) 140 and 240 km detections. The total intensity received in the 580 cm~1 frequency interval is 14 nW m~2 sr~1 and comprises about 20% of the total intensity expected from the energy release from nucleosynthesis throughout the history of the universe.