Large Area Lyman-Alpha survey

Sangeeta Malhotra
Space Telescope Science Institute

With the LALA survey we are finding populations of lyman-alpha
emitters at redshift 4.5 and 5.7. These sources are faint in
the continuum and majority would not be found except by
methods selecting bright line emission. The equivalent width
of the lyman-alpha line in more than half the objects is
higher than can be explained by normal stellar populations,
and could be due to AGNs, zero-metallicity stars or extreme
IMFs. The detection of lyman-alpha emitters also implies that
the universe is largely neutral at these redshifts