The SCUBA-2 Large eXtragalactic Survey: 850μm map, catalogue and the bright-end number counts of the XMM-LSS field

• Published in: Monthly notices of the Royal Astronomical Society Vol. 520; no. 3; pp. 3669 - 3687
• Main Authors: Garratt, T K, Geach, J E, Tamura, Y, Coppin, K E K, Franco, M, Ao, Y, Chen, C -C, Cheng, C, Clements, D L, Dai, Y S, Dannerbauer, H, Greve, T R, Hatsukade, B, Hwang, H S, Jiang, L, Kohno, K, Koprowski, M P, Michałowski, M J, Sawicki, M, Scott, D, Shim, H, Takeuchi, T T, Wang, W -H, Xue, Y Q, Yang, C
• Format: Journal Article
• Language: English
• Published: Oxford University Press 15.02.2023
• Subjects: catalogues; galaxies: high-redshift; submillimetre: galaxies; surveys; surveys; catalogues; submillimetre: galaxies; galaxies: high-redshift
• ISSN: 0035-8711; 1365-2966; 1365-2966
• DOI: 10.1093/mnras/stad307

ABSTRACT We present $850\, \mu {\rm m}$ imaging of the XMM-LSS field observed for 170 h as part of the James Clerk Maxwell Telescope SCUBA-2 Large eXtragalactic Survey (S2LXS). S2LXS XMM-LSS maps an area of $9\, {\rm deg}^2$, reaching a moderate depth of $1\sigma \simeq 4\, {\rm mJy\, beam^{-1}}$. This is the largest contiguous area of extragalactic sky mapped by James Clerk Maxwell Telescope (JCMT) at $850\, \mu {\rm m}$ to date. The wide area of the S2LXS XMM-LSS survey allows us to probe the ultra-bright ($S_{\rm 850\mu m}\gtrsim 15\, {\rm mJy}$), yet rare submillimetre population. We present the S2LXS XMM-LSS catalogue, which comprises 40 sources detected at >5σ significance, with deboosted flux densities in the range of $7$–$48\, {\rm mJy}$. We robustly measure the bright-end of the $850\, \mu {\rm m}$ number counts at flux densities ${\gt }7\, {\rm mJy}$, reducing the Poisson errors compared to existing measurements. The S2LXS XMM-LSS observed number counts show the characteristic upturn at bright fluxes, expected to be motivated by local sources of submillimetre emission and high-redshift strongly lensed galaxies. We find that the observed $850\, \mu {\rm m}$ number counts are best reproduced by model predictions that include either strong lensing or source blending from a 15-arcsec beam, indicating that both may make an important contribution to the observed overabundance of bright single dish $850\, \mu {\rm m}$ selected sources. We make the S2LXS XMM-LSS $850\, \mu {\rm m}$ map and >5σ catalogue presented here publicly available.