The comparable strengths of the observed UV/optical/IR and FIR/submillimeter extragalactic backgrounds support the suggestion that a significant fraction of the primary UV/optical photons associated with star formation are absorbed by dust grains. As a result of this heating to temperatures in the range 10 to 100 Kelvin, the dust then re-radiates this thermal energy at longer wavelengths. In order to understand the global history of star formation in more detail, a great deal of observational effort has been invested to spatially resolve the extragalactic background into the different populations of quiescent galaxies, starburst galaxies and AGN.

The first submillimeter and millimeter wavelength surveys (with SCUBA on the 15-m JCMT, and MAMBO on the 30-m IRAM, respectively) have detected a population of luminous high-redshift starburst galaxies. This same bright population produces 10-50% of the measured diffuse submillimeter extragalactic background. It is expected that, by going significantly deeper than the current confusion-limited observations, the next generation of (sub)millimeter surveys on larger telescopes will resolve 100% of this extragalactic background into individual galaxies.

The combination of the measured (sub)millimeter source-counts, and the redshift and spatial distributions of these dust-enshrouded starburst galaxies will enable us to understand their evolutionary history, their relationship (if any) with other populations of galaxies and AGN, and their association with larger-scale structures in the Universe.

BLAST will answer some of these questions by providing large-area, confusion-limited extragalactic surveys at 250, 350, and 500 μm. These next-generation surveys will measure the photometric redshifts and clustering properties of thousands of previously undetected, luminous starburst galaxies (L_FIR > 3x10¹² L_sun).

New!
During the 2006 long-duration flight from McMurdo Antarctica BLAST successfully delivered on the promise of conducting the widest submm extra-galactic blank-field surveys to date! We are currently extremely busy analyzing these data - stay tuned for the first results in early 2008!

The diagram below is a simulated 0.5 deg² extragalactic confusion-limited BLAST survey. The simultaneous multi-wavelength BLAST data are combined in this false-color image (blue: 250 μm, green: 350 μm, red: 500 μm) and are shown at the resolution of the 500 μm observations (approximately 60 arcsecs). This simulation is generated from a mock catalogue of strongly evolving starburst galaxies with a surface density and redshift distribution consistent with the current observational evidence. The differences in the individual colors of the submillimeter galaxies in this false-color image reflect their wide range of redshifts (and not intrinsic differences in their spectral energy distributions). This simulation demonstrates the ability of BLAST to measure photometric redshifts (with an error less than ±0.5) from the available color information between observations at 250, 350 and 500 μm. An extended foreground cirrus component is also included in the simulation. The 500 μm “footprint” of the BLAST array is shown in the top-left corner.