The FOVs of different observations used in this paper. The background: 8.0  μm (GLIMPSE). The FOVs of our deep IRAC imaging are shown with the dashed lines ([3.6] and [5.8] bands) and dotted lines ([4.5] and [8.0] bands). The dash-dotted lines present the FOV of the Chandra X-ray observation. The solid lines show the FOVs for VIMOS imaging and spectroscopy. The central line-filled regions were covered with HST observations.