Max Tegmark's cosmology library: y
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 5.
Click
here
if you are interested in
other research of mine.
If the net is slow, try selecting a different flag
under below.
DID THE UNIVERSE RECOMBINE?
NEW SPECTRAL CONSTRAINTS ON REHEATING
Authors:
Max Tegmark & Joe Silk
Abstract:
One still cannot conclusively assert that the
universe underwent a neutral phase, despite the new COBE FIRAS
limit y<0.000025 on
Compton y-distortions of the cosmic microwave background.
Although scenarios where the very early (z=1000) ionization is
thermal, caused by IGM temperatures exceeding 10000K, are clearly
ruled out, there is a significant loophole for cosmologies with
typical CDM parameters if the dominant ionization mechanism is
photoionization.
If the ionizing radiation has a typical quasar spectrum,
then the y-constraint implies roughly
h^{3/2}\Omega_b Omega_0^{-1/4}<0.1 for fully ionized models.
This means that BDM models with Omega_0 around 0.15 and reionization
at about z=1000 are strongly constrained even in this very
conservative case, and can survive the y test only if
most of the baryons form BDM around the reionization epoch.
Return to my home page
This page was last modified July 1, 1998.
max@ias.edu