IRAC colour-colour diagram for LDHD-detected sources. The black line denotes the region in which IRAC AGN are expected, as per the Donley et al. (2012) criteria. Faded grey squares indicate the LDHD-undetected sample, while the coloured symbols indicate LDHD-detected sources. White circles indicate sources with log₁₀T_b > 5.6 and white diamonds indicate sources with log₁₀T_b > 5.7. Sources with no dot or diamond have 5.5 ≤ log₁₀T_b ≤ 5.6, with the exception of the black star, which indicates the single source with log₁₀T_b < 5.5.