(a) Pixels used in the stacking analysis (black pixels were used and white pixels were not). Stacked Chandra images of (b) optically bright HDF‐N galaxies in the full band (7.7 Ms effective exposure), (c) optically bright HDF‐N galaxies in the soft band (7.7 Ms effective exposure), and (d) optically bright HDF‐N spiral galaxies in the full band (5.0 Ms effective exposure). The stacked images have been made using the restricted ACIS grade set, and they have been adaptively smoothed at the 2.5 σ level using the code of Ebeling et al. (2001). The images are 11^{﹩\arcsec﹩} × 11^{﹩\arcsec﹩} in size, and each pixel is 0﹩\farcs﹩5 on a side. In all images north is up, and east is to the left. The circle in each image is centered on the stacking position and has a radius of 1﹩\farcs﹩5. The white contours are drawn at 75%, 85%, and 95% of the maximum pixel value.