A Redshift-Magnitude Relation for Non-Uniform Pressure Universes
  A redshift-magnitude relation for the two exact non-uniform pressure
spherically symmetric Stephani universes is presented. The Kristian-Sachs
method expanding the relativistic quantities in series is used, but only first
order terms in redshift $z$ are considered. The numerical results are given
both for centrally placed and non-centrally placed observers. In the former
case the redshift-magnitude relation does not depend on the direction in the
sky and the Friedman limit can be easily performed. It appears that the effect
of spatial dependence of pressure is similar to the effect of the deceleration
parameter in Friedman models. In the latter case the angular dependence of the
relation is important. This may serve as another possible explanation of the
non-compatibility of the theoretical curve of the redshift-magnitude relation
with observations for large redshift objects in the Friedman universe. On the
other hand, comparing the magnitudes of equal redshifts objects in different
directions in the sky, one can test the reliability of these models.
