BLAST sources at 250, 350 and 500um

In the redshift range 1 less than or equal to z less than or equal to 4, these massive submillimetre galaxies go through a phase characterized by optically obscured star formation at rates several hundred times that in the local Universe. Half of the starlight from this highly energetic process is absorbed and thermally re-radiated by clouds of dust at temperatures near 30K with spectral energy distributions peaking at 100um in the rest frame.

At 1 less than or equal to z less than or equal to 4, the peak is redshifted to wavelengths between 200 and 500um. The cumulative effect of these galaxies is to yield extragalactic optical and far-infrared backgrounds with approximately equal energy densities. Since the initial detection of the far-infrared background (FIRB), higher-resolution experiments have sought to decompose this integrated radiation into the contributions from individual galaxies.