**AAS 197, January 2001**

*Session 56. Frontiers of Astrophysics III*

Joint Special Session Oral, Tuesday, January 9, 2001, 10:30am-12:00noon, Town and Country
[Previous] |
[Session 56] |
[Next]

## [56.01] New Evidence for Neutrino Degeneracy in the Early Universe

*G. Mathews (U. Notre Dame), T. Kajino, M. Orito (National Astronomical Observatory, Japan)*

We reanalyze cosmological constraints on the existence of a
net universal lepton asymmetry and neutrino degeneracy in
light of reanalyzed primordial nucleosynthesis and the
recently reported CMB power spectra from BOOMERANG and
MAXIMA-1. We explore physically plausible lepton-asymmetric
models with large \nu_{\mu} and \nu_{\tau} degeneracies
together with a moderate \nu_{e} degeneracy. We show that
primordial nucleosynthesis by itself permits very large
neutrino degeneracies 0. \le \xi_{\nu_{\mu}},
\xi_{\nu_{\tau}} \le 40, 0. \le
\xi_{\nu_{e}} \le 1.4 together with large baryon
densities 0.1 \le \Omega_{b} h^{2}_{50} \le 1 as
long as some destruction of primordial lithium is assumed.
We also show that structure formation and the power spectrum
of the cosmic microwave background allows for the
possibility of an \Omega = 1, \Omega_{\}Lambda = 0.4,
cosmological model for which there is both significant
lepton asymetry (\vert \xi_{\nu_{\mu}} \vert =
\vert \xi_{\nu_{\tau}} \vert \approx 11) and a
relatively large baryon density (\Omega_{b} \approx 0.06).
The best neutrino asymmetric models naturally accommodate
the observed suppression of the second acoustic peak in the
CMB spectrum. Goodness of fit contours show a well developed
minimum with degeneracy parameter \xi_{\nu_\mu} =
\xi_{\nu_\tau} \approx 2, \xi_{\nu_e} \approx 0.1, and
\Omega_{b} h_{50}^{2} \approx 0.1 for a broad range of
cosmological parameters.

The author(s) of this abstract have provided an email address
for comments about the abstract:
gmathews@nd.edu

[Previous] |
[Session 56] |
[Next]