AEGIS: Chandra Observation of DEEP2 Galaxy Groups and Clusters

We present a 200 ks Chandra observation of seven spectroscopically selected, high-redshift (0.75 < z < 1.03) galaxy groups and clusters discovered by the DEEP2 Galaxy Redshift Survey in the Extended Groth Strip. X-ray emission at the locations of these systems is consistent with background. The 3 σ upper limits on the bolometric X-ray luminosities (LX) of these systems put a strong constraint on the relation between LX and the velocity dispersion of member galaxies σgal at z ~ 1; the DEEP2 systems have lower luminosity than would be predicted by the local relation. Our result is consistent with recent findings that at high redshift, optically selected clusters tend to be X-ray-underluminous. A comparison with mock catalogs indicates that it is unlikely that this effect is entirely caused by a measurement bias between σgal and the dark matter velocity dispersion. Physically, the DEEP2 systems may still be in the process of forming and hence not fully virialized, or they may be deficient in hot gas compared to local systems. We find only one possibly extended source in this Chandra field, which happens to lie outside the DEEP2 coverage.