XXIVth IAP Colloquium

Far away : light in the young universe at redshift beyond three

Monday July 7 to Friday July 11, 2008

List of RHOADS's Presentation(s) ( Updated 20/01/2011 15:11:24 )

Precise if your presentation is oral or a poster : Oral
Title of your presentation : Lyman Alpha Tests of Reionization

Lyman alpha galaxies provide a unique probe of cosmological reionization.
Because Lyman alpha photons are scattered by neutral hydrogen, the
observed presence of Lyman alpha emitting galaxies requires an IGM that
is predominantly ionized. The Lyman alpha tests are local and probe the
central phase of reionization. They thereby complement the Gunn-Peterson
test, which is sensitive to neutral fractions around 1%, and the microwave
background polarization, which provides integrated constraints on
ionized gas at 6 < z < 30, but no local information.
I will review the physics underlying Lyman alpha reionization tests.
Tests based on the Lyman alpha luminosity function have reached
a range of conclusions, with some authors finding upper limits on the
neutral fraction (Malhotra & Rhoads 2004, Stern et al 2005) and others
arguing in favor of a substantially neutral IGM (Kashikawa et al 2006,
Iye et al 2007, Ota et al 2008). To break this impasse, we can turn
to other tests based on the same physics, such as the volume test
(Malhotra & Rhoads 2006) and clustering statistics (Furlanetto 2006,
McQuinn et al 2007), both of which seem to favor a largely ionized medium.
I will close with a discussion of future prospects for these methods,
which are bright: Larger samples at redshift 6 and moderate samples
up to redshift 9 are expected from a range of ongoing projects.

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