LINEAR PHASES
Cosmological models based on variants
of the standard CDM scenario have been proposed by many authors. In my
PhD thesis [4] I have studied the
linear spectra evolution of a CDM
model with a massive neutrino component(CHDM). For several years CHDM models
have been considered to provide a good fit to clustering data, but the
recent strong observational evidence for a nonzero cosmological constant
has ruled out these models. The Kamiokande experiment showed that neutrinos
have a nonzero rest mass, so it has been studied the possible influence
on the primeval spectrum P(k) of a CDM cosmology , dominated by
a term ( CDM
models), of a small neutrino mass m[8].
The main points are :

Linear density evolution has been considered
for the formation of large scale structures in flat cosmologies with
>0 (currently
very popular) and m>0
(as
demanded by Kamiokande)

The results show that the shape
of the final spectra is governed by the ratio /_{M
}and
even neutrinos with 0.01 < m
< 0.1 can induce strong changes
in the final P(k)

Linear analysis shows that consistency
with clustering data is obtained for h=0.7, _{M}~
0.4 and 0.05 < /_{M
}<
0.1 ( m ~ 0.1 1
eV)
This line of research is currently
in standby... Possible developments : T
/T , clustering evolution, numerical simulations.
Other research subjects investigated
in the linear regime have been the smallscale anisotropies of the cosmic
background radiation [2,5]and its polarization [6].
Related Publications:

[1] Bonometto, S.A., Valdarnini, R., 1984, Nature of dark matter and
pancake mass, Phys. Lett., 103A, 369.

[2] Bonometto, S.A., Lucchin, F., Valdarnini, R., 1984, Small scale
anisotropies of the microwave background in model universes dominated by
dark matter, Astr. and Astrophys., 140, L27.

[3] Valdarnini, R., 1985, Evolution of adiabatic perturbations in a
photino dominated universe, Astron. and Astrophys., 143, 94.

[4] Valdarnini, R., Bonometto, S.A., 1985, Fluctuation evolution in
a twocomponent dark matter model, Astron. and Astrophys. , 146,
235.

[5] Bonometto, S.A., Valdarnini, R., 1985,MW background anisotropies,
large scale peculiar velocity fields, clustering evolution in a warmhot
dark matter cosmological model, Ap.J.Lett., 299, L71

[6] Milaneschi, E., Valdarnini, R., 1986, Small scale polarization of
the cosmic background radiation, Astron. and Astrophys. ,162,
5.

[7] Guzzo, L. Branchini, E. & Valdarnini , R. ,1994,Reconstructing
the Power Spectrum of Density Fluctuations, ApJL, 424, L5.

[8] Valdarnini, R., Kahniashvili T. & Novosyadlyj B. , 1998, Large
Scale Structure Formation in MDM models with a Cosmological Costant, Astr.
& Astrophys., 336, 11.