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We use deep Chandra imaging and an extensive optical spectroscopy campaign onthe Keck 10-m telescopes to study the properties of X-ray point sources in fivelarge-scale structures at redshifts of z ~ 0.7-0.9. We first study X-ray pointsources using the statistical measure of cumulative source counts, finding thatthe measured overdensities are consistent with previous results, but werecommend caution in overestimating the precision of the technique. Opticalspectroscopy of objects matched to X-ray point sources confirms a total of 27AGN within the five structures, and we find that their host galaxies tend to belocated away from dense cluster cores. More than 36% of host galaxies arelocated in the `green valley', which suggests they are a transitionalpopulation. Based on analysis of OII and Hd line strengths, the averagespectral properties of the AGN host galaxies in all structures indicate eitheron-going star formation or a starburst within ~ 1 Gyr, and the host galaxiesare younger than the average galaxy in the parent population. These resultsindicate a clear connection between starburst and nuclear activity. We usecomposite spectra of the spectroscopically confirmed members in each structureto separate them based on a measure of the overall evolutionary state of theirconstituent galaxies. We define structures as having more evolved populationsif their average galaxy has lower EW(OII) and EW(Hd). The AGN in the moreevolved structures have lower rest-frame 0.5-8 keV X-ray luminosities (allbelow 10^43.3 erg s^-1) and longer times since a starburst than those in theless evolved structures, suggesting that the peak of both star formation andAGN activity has occurred at earlier times. With the wide range of evolutionarystates and timeframes in the structures, we use our results to analyze theevolution of X-ray AGN and evaluate potential triggering mechanisms.

The Evolution and Environments of X-ray Emitting Active Galactic Nuclei in High-Redshift Large-Scale Structures