We summarize the multiwavelength properties of X-ray sources detected in the
80 ks XMM-Newton observation of the Groth-Westphal Strip. We find 23 XMM-Newton
sources within the WFPC2 fields. Ten spectroscopic redshifts are available from
the DEEP and CFRS projects and 4 of these show broad Mg II emission (type 1
AGNs). Two of those without any broad lines, nevertheless, have [NeV] emission
which is an unambiguous signature of AGN activity, one of which is a
narrow-line Seyfert 1 and the other a type 2 AGN. We have made near-infrared
(NIR) spectroscopic observations using the Subaru OHS/CISCO spectrometer for
five of the X-ray sources for which we found no indication of an AGN activity
in the optical spectrum. We have detected H-alpha+[NII] emission in four of
them. A broad H-alpha component and/or a large [NII]/H-alpha ratio is seen,
suggestive of AGN activity. Nineteen sources have been detected in the Ks band
and four of these are extremely red objects (I814-Ks>4). The optical
counterparts for the majority of the X-ray sources are bulge-dominated with
colors consistent with evolving elliptical galaxies, with starburst/AGN
contamination. Assuming that the known local relations among the bulge
luminosity,central velocity dispersion, and the mass of the central blackhole
hold at about z=1, the AGN bolometric luminosity to Eddington luminosity ratio
ranges from 0.3% to 10%. (abridged)Comment: 18 pages, 6 figures, accepted for publication in Astronomical Journa