Figure 12: Cumulative fractional contribution of CT AGN to the XRB in the 14–195 keV Swift/BAT band as a function of redshift from population synthesis models [35]. As shown by the vertical dashed lines, 50%, 80%, and 90% of the total CT AGN contribution come from sources at , 1.4, and 2.0, respectively. Only ~1% of the total XRB intensity comes from CT AGN at . The data point at corresponds to the contribution to the XRB by the CT AGN detected by Swift/BAT, while the data points at high redshift were obtained from the CT AGN in the CDF-S [70]. Solid error bars correspond to transmission-dominated sources only, while the data points with dashed error bars include all the sources in the sample.