We present the results of Chandra observations of the Cl1604 supercluster at z \sim 0.9 .
The system is the largest structure mapped at redshifts approaching unity , containing at least eight spectroscopically confirmed galaxy clusters and groups .
Using two 50-ksec ACIS-I pointings we examine both the X-ray point source population and the diffuse emission from individual clusters in the system .
We find a 2.5 \sigma excess of point sources detected in the hard band ( 2-10 keV ) relative to the number of sources found in blank fields observed by Chandra .
No such excess is observed in the soft band ( 0.5-2 keV ) .
The hard-band source density is 1.47 times greater than that of a blank field , in agreement with the previously reported correlation between overdensity amplitude and cluster redshift .
Using a maximum likelihood technique we have matched 112 of the 161 detected X-ray point sources to optical counterparts and found 15 sources that are associated with the supercluster .
All 15 sources have rest-frame luminosities consistent with emission from active galactic nuclei ( AGN ) .
We find that the supercluster AGN largely avoid the densest regions of the system and are instead distributed on the outskirts of massive clusters or within poorer clusters and groups .
We have also detected diffuse emission from two of the eight clusters and groups in the system , clusters Cl1604+4304 and Cl1604+4314 .
The systems have bolometric luminosities of 1.43 \times 10 ^ { 44 } and 8.20 \times 10 ^ { 43 } h _ { 70 } ^ { -2 } erg s ^ { -1 } and gas temperatures of 3.50 ^ { +1.82 } _ { -1.08 } and 1.64 ^ { +0.65 } _ { -0.45 } keV , respectively .
Using updated velocity dispersions , we compare the properties of these systems to the cluster scaling relations followed by other X-ray and optically selected galaxy clusters at high redshift .