Max Tegmark's cosmology library: openreion
Please click here to download the paper
described below.
Since this postscript file does not include the figures, I strongly
suggest that you download my
Ph.D. thesis
instead, in which this paper constitutes Chapter 4.
Click
here
if you are interested in
other research of mine.
REIONIZATION IN AN OPEN CDM UNIVERSE:
IMPLICATIONS FOR COSMIC MICROWAVE BACKGROUND FLUCTUATIONS
Authors:
Max Tegmark & Joe Silk
Abstract:
We generalize
previous work
on early photoionization
to CDM models with Omega<1.
Such models have received recent interest because
the excess power in the large-scale galaxy distribution
is phenomenologically fit if the ``shape parameter"
Gamma=h Omega_0 is about 0.25.
It has been argued that such models may require early
reionization to suppress small-scale anisotropies
in order to be consistent with experimental data.
We find
that if
the cosmological constant lambda=0, the extent of this suppression is
quite insensitive to Omega_0.
Given a sigma_8-normalization today,
the loss of small-scale power associated
with a lower Omega_0 is partially canceled by higher optical depth from
longer lookback times and by structures forming at higher
redshifts before
the universe becomes curvature-dominated.
The maximum angular scale on which fluctuations are
suppressed decreases when Omega_0 is lowered,
but this effect is also rather weak and unlikely to be
measurable in the near future.
For flat models, on the other hand, where
lambda_0 = 1-Omega_0, the negative effects of lowering Omega_0
dominate, and early reionization is not likely to play a
significant role if Omega_0<<1. The same applies to
CDM models
where the effective Gamma is lowered by increasing the number of
relativistic particle species.
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This page was last modified July 1, 1998.
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