Figure 15: Photometric redshift distribution for 90 sources in the ECDF-S in the mid-IR excess region. The solid histogram shows the distribution for the sources not detected in X-rays, while the dashed hatched histogram considers only the X-ray-detected sources. A KS test shows that it is perfectly likely (~16%) that these two distributions were drawn from the same parent distribution. The dotted histogram shows the slightly lower redshift distribution (divided by 1,000) for all the sources with a 24 μm detection and a measured photometric redshift in the ECDF-S.