The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) has made one square degree, deep, confusion limited maps at three different bands, centered on the Great Observatories Origins Deep Survey South field. By calculating the covariance of these maps with catalogs of 24 µm sources from the Far-Infrared Deep Extragalactic Legacy Survey (FIDEL), we have determined that the total submillimeter intensities are 8.60 ± 0.59, 4.93 ± 0.34, and 2.27 ± 0.20 nW m −2 sr −1 at 250, 350, and 500 µm, respectively. These numbers are more precise than previous estimates of the cosmic infrared background (CIB) and are consistent with 24 µm-selected galaxies generating the full intensity of the CIB. We find that the fraction of the CIB that originates from sources at z ≥ 1.2 increases with wavelength, with 60% from high redshift sources at 500 µm. At all BLAST wavelengths, the relative intensity of high-z sources is higher for 24 µm-faint sources than it is for 24 µm-bright sources. Galaxies identified as active galactic nuclei (AGN) by their Infrared Array Camera (IRAC) colors are 1.6-2.6 times brighter than the average population at 250-500 µm, consistent with what is found for X-ray-selected AGN. BzK-selected galaxies are found to be moderately brighter than typical 24 µmselected galaxies in the BLAST bands. These data provide high precision constraints for models of the evolution of the number density and intensity of star forming galaxies at high redshift.

Submillimetre surveys during the past decade have discovered a population of luminous, high-redshift, dusty starburst galaxies [1][2][3][4][5][6][7][8] . In the redshift range 1 ≤ z ≤ 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 reradiated by clouds of dust at temperatures near 30 K with spectral energy distributions peaking at 100 μm in the rest frame 9 . At 1 ≤ z ≤ 4, the peak is redshifted to wavelengths between 200 and 500 μm. 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 respectively. The depth of the BGS-Deep map was chosen to produce maps that have high signal-to-noise ratios and in which the fluctuations are dominated by pixel-to-pixel fluctuations in signals from galaxies rather than detector noise. The BLAST map ( Fig. 1) overlaps some of the deepest multiwavelength data that exist in a cosmological survey, including radio, infrared, optical (Hubble Ultra Deep Field ) and X-ray (Extended Chandra Deep Field-South) surveys 13,14 . The BGS-Wide map was designed to match the coverage area and sensitivity of the near-infrared and mid-infrared Spitzer Wide-area Infrared Extragalactic survey 15 . By considering both of the data sets together, we derive a catalogue of sources that covers a large dynamic range, (a factor of 50 in flux density)with sufficient sensitivity to resolve the FIRB into individual galaxies. The area is largePage 3 of 12 enough that the source counts are minimally affected by clustering. The BLAST survey contains approximately 500 sources with significant (>5σ) detections.The brightness distribution, or number counts, of submillimetre sources probes the luminosity function in relation to redshift and can be used to constrain models for the formation and evolution of dusty, star-forming galaxies. Models that simultaneously fit the entire range of existing data (24-850 μm) include at least two distinct galaxy populations with different spectral energy distributions and evolutionary histories 16,17 .The BLAST data uniquely bridge these wavelengths across the energetic peak in the FIRB, and provide new strong constraints on the details of the evolution of these populations.The number counts cannot be obtained directly from the distribution of detected sources in the BLAST catalogues because of several well-known biases. (1) Rather than attempting to correct our source list for each of these effects, we estimate the counts from the distribution of pixel brightnesses in the entire map. This P(D) analysis 19 implicitly handles all of the effects mentioned above, yet uses more of the information available to us than just the brightest pixels of the extracted point sources in our catalogues. Figure 2 shows the BLAST number counts with the results f...

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a sub-orbital surveying experiment designed to study the evolutionary history and processes of star formation in local galaxies (including the Milky Way) and galaxies at cosmological distances. The BLAST continuum camera, which consists of 270 detectors distributed between 3 arrays, observes simultaneously in broadband (30%) spectral-windows at 250, 350, and 500 µm. The optical design is based on a 2 m diameter telescope, providing a diffraction-limited resolution of 30 ′′ at 250 µm. The gondola pointing system enables raster mapping of arbitrary geometry, with a repeatable positional accuracy of ∼ 30 ′′ ; post-flight pointing reconstruction to 5 ′′ rms is achieved. The on-board telescope control software permits autonomous execution of a pre-selected set of maps, with the option of manual override. In this paper we describe the primary characteristics and measured in-flight performance of BLAST. BLAST performed a test-flight in 2003 and has since made two scientifically productive long-duration balloon flights: a 100-hour flight from ESRANGE (Kiruna), Sweden to Victoria Island, northern Canada in June 2005; and a 250-hour, circumpolar-flight from McMurdo Station, Antarctica, in December 2006.

We detect correlations in the cosmic far-infrared background due to the clustering of star-forming galaxies in observations made with the Balloon-borne Large Aperture Submillimeter Telescope, BLAST, at 250, 350, and 500 µm. We perform jackknife and other tests to confirm the reality of the signal. The measured correlations are well fit by a power law over scales of 5-25 arcminutes, with ∆I/I = 15.1 ± 1.7%. We adopt a specific model for submillimeter sources in which the contribution to clustering comes from sources in the redshift ranges 1.3 ≤ z ≤ 2.2, 1.5 ≤ z ≤ 2.7, and 1.7 ≤ z ≤ 3.2, at 250, 350 and 500 µm, respectively. With these distributions, our measurement of the power spectrum, P (k θ ), corresponds to linear bias parameters, b = 3.8 ± 0.6, 3.9 ± 0.6 and 4.4 ± 0.7, respectively. We further interpret the results in terms of the halo model, and find that at the smaller scales, the simplest halo model fails to fit our results. One way to improve the fit is to increase the radius at which dark matter halos are artificially truncated in the model, which is equivalent to having some star-forming galaxies at z ≥ 1 located in the outskirts of groups and clusters. In the context of this model we find a minimum halo mass required to host a galaxy is log(M min /M ⊙ ) = 11.5 +0.4 −0.1 , and we derive effective biases b eff = 2.2 ± 0.2, 2.4 ± 0.2, and 2.6 ± 0.2, and effective masses log(M eff /M ⊙ ) = 12.9 ± 0.3, 12.8 ± 0.2, and 12.7 ± 0.2 , at 250, 350 and 500 µm, corresponding to spatial correlation lengths of r 0 = 4.9, 5.0, and 5.2 ± 0.7 h −1 Mpc, respectively. Finally, we discuss implications for clustering measurement strategies with Herschel and Planck.

We describe the application of a statistical method to estimate submillimeter galaxy number counts from confusion limited observations by the Balloon-borne Large Aperture Submillimeter Telescope (BLAST). Our method is based on a maximum likelihood fit to the pixel histogram, sometimes called 'P (D)', an approach which has been used before to probe faint counts, the difference being that here we advocate its use even for sources with relatively high signal-to-noise ratios. This method has an advantage over standard techniques of source extraction in providing an unbiased estimate of the counts from the bright end down to flux densities well below the confusion limit. We specifically analyse BLAST observations of a roughly 10 deg 2 map centered on the Great Observatories Origins Deep Survey South field. We provide estimates of number counts at the three BLAST wavelengths, 250, 350, and 500 µm; instead of counting sources in flux bins we estimate the counts at several flux density nodes connected with power-laws. We observe a generally very steep slope for the counts of about −3.7 at 250 µm and −4.5 at 350 and 500 µm, over the range ∼0.02-0.5 Jy, breaking to a shallower slope below about 0.015 Jy at all three wavelengths. We also describe how to estimate the uncertainties and correlations in this method so that the results can be used for model-fitting. This method should be well-suited for analysis of data from the Herschel satellite.