The SCUBA Half-Degree Extragalactic Survey - II. Submillimetre maps, catalogue and number counts

Abstract

We present maps, source catalogue and number counts of the largest, most complete and unbiased extragalactic submillimetre survey: the 850‐μm SCUBA Half‐Degree Extragalactic Survey (SHADES). Using the Submillimetre Common‐User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT), SHADES mapped two separate regions of sky: the Subaru/XMM–Newton Deep Field (SXDF) and the Lockman Hole East (LH). Encompassing 93 per cent of the overall acquired data (i.e. data taken up to 2004 February 1), these SCUBA maps cover 720 arcmin2 with a rms noise level of about 2 mJy and have uncovered >100 submillimetre galaxies. In order to ensure the utmost robustness of the resulting source catalogue, data reduction was independently carried out by four subgroups within the SHADES team, providing an unprecedented degree of reliability with respect to other SCUBA catalogues available from the literature. Individual source lists from the four groups were combined to produce a robust 120‐object SHADES catalogue; an invaluable resource for follow‐up campaigns aiming to study the properties of a complete and consistent sample of submillimetre galaxies. For the first time, we present deboosted flux densities for each submillimetre galaxy found in a large survey. Extensive simulations and tests were performed separately by each group in order to confirm the robustness of the source candidates and to evaluate the effects of false detections, completeness and flux density boosting. Corrections for these effects were then applied to the data to derive the submillimetre galaxy source counts. SHADES has a high enough number of detected sources that meaningful differential counts can be estimated, unlike most submillimetre surveys which have to consider integral counts. We present differential and integral source number counts and find that the differential counts are better fit with a broken power law or a Schechter function than with a single power law; the SHADES data alone significantly show that a break is required at several mJy, although the precise position of the break is not well constrained. We also find that a 850‐μm survey complete down to 2 mJy would resolve 20–30 per cent of the far‐infrared background into point sources.

The Gismo Two-Millimeter Deep Field in Goods-N

“…Thus, in a statistical ensemble of sources, the same observed flux arises more often from one of many fainter sources than from the few brighter ones, relative to the measured value. We assume a measurement with Gaussian noise (validated by the closely Gaussian jackknife noise distribution) and a 2 mm source count model scaled from observationally constrained 850 μm counts (e.g., Coppin et al 2006;Weiß et al 2009…”

“…For deboosting we followed a Bayesian recipe, such as described in Coppin et al (2005Coppin et al ( , 2006:…”

Almacal I: First Dual-Band Number Counts From a Deep and Wide Alma Submillimeter Survey, Free From Cosmic Variance

“…These relatively bright SMGs, which have a median redshift of z∼2.3 and SFR  100 M e yr −1 (Chapman et al 2005), have traditionally been found using bolometer cameras, such as the Submmillimetre Common-User Bolometer Array (SCUBAHolland et al 1999), mounted on single-dish telescopes, such as the 15 m James Clerk Maxwell Telescope (e.g., Coppin et al 2006;Weiß et al 2009b;Wardlow et al 2011;Casey et al 2013;Geach et al 2013). One of the main advantages of single-dish observations is that they can survey sufficiently wide areas of the sky to enable the detection of relatively large numbers of galaxies.…”

Properties of the Scuba-2 850㎛ Sources in the XMM-LSS Field

“…Results in Figure 7 were derived from observation data taken by instruments with the same angular resolution (i.e., SCUBA and SCUBA-2). Coppin et al (2006) and Casey et al (2013) estimated number counts down to 2 mJy using sources in blank-field. The limitation of faint end flux density is related to the confusion limit.…”

“…• 00 ′ 00 ′′ ) is one of two regions in SHADES where number count (Coppin et al 2006), redshift distribution (Aretxaga et al 2007;Ivison et al 2007;Clements et al 2008) and physical parameters of SMGs (Clements et al 2008) were investigated. In this study, we also investigate number count and physical properties of SMGs in blank-field using 850 µm imaging data centered at (α 2000 , δ 2000 ) = (02 h 18 m 07 s , -04…”