Left panel: entire CDF-S image after point-source removal. Green square is the spectral extraction region. Right panel: represents the spectral fitting result. Data (crosses) and best-fit models (thick solid lines) are shown for four ACIS-I CCDs. Upper and lower panels: indicate the count rate and data-to-model ratio, respectively. The particle-induced background models are shown with thin solid lines. The unresolved CXB models are indicated with dashed lines. The 0.7–9.0 keV range was used for the spectral fit. Two energy ranges, 2.0–2.4 keV and 7.2–7.8 keV, were excluded from analysis.