Multiwavelength study of S2CLS/NEPSC2 sources

In order to overcome the large beam size (15 arcsec) of the 850-{mu}m images, deep optical to near-infrared (NIR) photometric data and arcsecond-resolution 20-cm images are used to identify counterparts of submillimetre sources. Among 647 sources, we identify 514 reliable counterparts for 449 sources (69 per cent in number), based either on probabilities of chance associations calculated from positional offsets or offsets combined with the optical-to-NIR colours.

In the radio imaging, the fraction of 850-{mu}m sources having multiple counterparts is 7 per cent. The photometric redshift, infrared luminosity, stellar mass, star formation rate (SFR), and the active galactic nucleus (AGN) contribution to the total infrared luminosity of the identified counterparts are investigated through spectral energy distribution fitting. The SMGs are infrared-luminous galaxies at an average <z> = 2.5 with log10(L_IR_/L_{sun}_) = 11.5-13.5, with a mean stellar mass of log10(M_star_/M_{sun}_) = 10.90 and SFR of log10(SFR/M_{sun}_.yr^-1^)=2.34.