The Lyman-α emitters found at z=4.5 and 5.7 by the Large Area Lyman Alpha (LALA) survey have high equivalent widths in the Lyman-α line. Such lines can be produced by narrow-lined active galactic nuclei (AGNs) or by stellar populations with a very high proportion of young, massive stars. To check for Type-II (i.e., narrow-lined) quasars, we obtained a deep X-ray image of 49 Lyman-α sources in a single field of the ACIS instrument on the Chandra X-ray Observatory. None of these sources were detected with a 3σ limiting X-ray luminosity of 2.9 × 10 43 ergs/s. For comparison, the two known high redshift type-II quasars have luminosities of 4 × 10 43 ergs/s before extinction correction. The sources remain undetected in stacked images of the 49 Lyman-α sources (with 6.5 Ms effective Chandra on-axis exposure) at 3σ limits of 4.9 × 10 42 . The resulting X-ray to Lyman-α ratio is about 4-24 times lower than the ratio for known type-II quasars, while the average Lyman-α luminosity of the LALA sample is in between the two type-II's. The cumulative X-ray to Lyman-α ratio limit is also below that of 90% of low-redshift Seyfert galaxies.
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