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 non-zero cosmological constant  has ruled out these models. The Kamiokande experiment showed that neutrinos have a non-zero 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 stand-by... Possible developments : T /T , clustering evolution, numerical simulations.

Other research subjects investigated in the linear regime have been the small-scale 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 two-component 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 warm-hot 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.