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A significant fraction of the sub-damped Lyman-alpha (sub-DLA) absorptionsystems in quasar spectra appear to be metal-rich, many with even super-solarelement abundances. This raises the question whether some sub-DLAs may harboractive galactic nuclei (AGN) since supersolar metallicities are observed inAGN. Here we investigate this question based on a mini-survey of 21 quasarsknown to contain sub-DLAs in their spectra. The X-ray observations wereperformed with the Chandra X-ray Observatory. In cases of no detection weestimated upper limits of the X-ray luminosities of possible AGNs at theredshifts of the sub-DLAs. In six cases we find possible X-ray emission within~ 1 arcsec of the background quasar consistent with the presence of a nearbyX-ray source. If these nearby X-ray sources are at the redshifts of thesub-DLAs, their estimated 0.2-10 keV luminosities range between 0.8 x10^{44}h^{-2} and 4.2 x 10^{44}h^{-2} erg s^{-1}, thus ruling out a normallate-type galaxy origin, and suggesting that the emission originates in agalactic nucleus near the center of a protogalaxy. The projected distances ofthese possible nearby X-ray sources from the background quasars lie in therange of 3-7 h^{-1} kpc, consistent with our hypothesis that they representAGNs centered on the sub-DLAs. Deeper follow-up X-ray and optical observationsare required to confirm the marginal detections of X-rays from these sub-DLAgalaxies.

A Mini X-Ray Survey of Sub-DLAs; Searching for AGNs Formed in Protogalaxies