  This work is related to different questions within cosmology. The principal
idea herein is to develop cosmological knowledge making use of the analyses of
observational data in order to find the values of the matter density Omega_m
and vacuum energy density Omega_Lambda.
  Data fitting is carried out using two statistical methods, chi^2 and maximum
likelihood. The data analysis exhibits that a low density and flat Universe is
strongly favoured.
  Applying the Omega_m value found for clusters of galaxies, we demonstrate
that clusters have very little room for baryonic dark matter. An upper limit to
the small but non-negligible sum of baryonic dark matter and galaxy mass can be
estimated, requiring the use of special statistics.
  A Toroidal Black Hole (TBH) study, in contrast to the Spherical Black Hole
(SBH), shows that the TBH can be used as an important tool in explaining AGN
phenomena.
