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The Lyman-alpha emitters found at z ~ 4.5 by the Large Area Lyman Alpha(LALA) survey have high equivalent widths in the Lyman-alpha line, which can beproduced by either narrow-lined active galactic nuclei (AGNs) or by stellarpopulations with a very high proportion of young, massive stars. To investigatethe AGN scenario, we obtained two deep Chandra exposures to study the X-raynature of the Lyman-alpha emitters. The 172 ks deep Chandra image on the LALABootes field was presented in a previous paper (Malhotra et al. 2003), and inthis paper we present a new Chandra deep exposure (174 ks) on the LALA Cetusfield, which doubled our sample of X-ray imaged Lyman-alpha sources, and imagedthe brightest source among our Lyman-alpha emitters. None of the 101Lyman-alpha sources covered by two Chandra exposures was detected individuallyin X-ray, with a 3 sigma limiting X-ray flux of F_{0.5-10.0 keV} < 3.3 x10^{-16} ergs/cm^2/s for on-axis targets. The sources remain undetectable inthe stacked image, implying a 3 sigma limit to the average luminosity ofL_{2-8keV} < 2.8 x 10^{42} ergs/s. The resulting X-ray to Lyman-alpha ratio is> 21 times lower than the ratios for known high redshift type-II quasars.Together with optical spectra obtained at Keck, we conclude that no evidence ofAGN activity was found among our Lyman-alpha emitters at z ~ 4.5.Comment: 12 pages, including 4 figures, ApJ letter accepte

X-Ray Nondetection of the Lyα Emitters at z ~ 4.5