2002ApJ...576L...1H -
Astrophys. J., 576, L1-L4 (2002/September-1)
The detectability of high-redshift Lyα emission lines prior to the reionization of the Universe.
HAIMAN Z.
Abstract (from CDS):
For a source of Lyα radiation embedded in a neutral intergalactic medium (IGM) prior to the reionization epoch, the Lyα emission line is strongly suppressed by the intervening IGM. The damping wing of the so-called Gunn-Peterson trough can extend to the red side of the emission line and erase a significant fraction of the total line flux. However, the transmitted fraction increases with the size of the local cosmological H II region surrounding the source, and therefore with the ionizing luminosity and age of the source. Motivated by the recent discovery of a Lyα-emitting galaxy at a redshift z=6.56 (Hu et al.), possibly prior to the reionization of the IGM, we revisit the effects of a neutral IGM on the Lyα emission line. We show that for faint sources with little or even no ionizing continuum, a sufficiently broad (Δv≳300 km.s–1) emission line can still remain observable. In particular, the line detected by Hu et al. is consistent with a source embedded in a neutral IGM. We provide characterizations of the asymmetry and total transmitted flux of the Lyα line as functions of the ionizing emissivity of its source. We argue that a statistical sample of Lyα emitters extending beyond the reionization redshift can be a useful probe of reionization.
Abstract Copyright:
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Journal keyword(s):
Cosmology: Theory - Cosmology: Early Universe - Galaxies: Formation
CDS comments:
Galaxy HCDM 6A at z = 6.56 is [HCM2002] 6A
Simbad objects:
3
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