COSTA, F. S. M.; http://lattes.cnpq.br/8938378819014229; COSTA, Felipe Sérvulo Maciel.
Resumo:
About twenty years ago, two groups of researchers studying the apparent brightness
of type Ia super nova e (SNe Ia), independently discovered that the current expansion of
the universe is accelerated. This discovery launched astronomy in to the dark energy
era, an energy component that, with in the theory of general relativity, is responsible for
the cosmic acceleration. However, the presence of a cosmic opacity in SNe Ia data may
mimicthe behavior of a dark component. Now a days, although the cosmic acceleration
is supported by other astronomical observations, a possible presence of opacity in the
SNe Ia data can lead to errors in the cosmological parameter estimates. Thus, several
works in the literature have investigated the universe's transparency hypothesis using
measurement so fluminosity distances of standard candles, suchas SNe Ia and gamma
ray bursts (GRBs), and distances obtained of the cosmic expansion rate H(z). These last
ones being independent of the cosmic transparency hypothesis. In this dissertation, we
make a bibliographical review on these works and new limits on opacity were placed with
the latest data of GRB sand H(z) in the context of the standard model. We have found
that the cosmic transparency hypothesis is in agreement with the data, but the results
from the observations of GRBs, which reach z > 9, where z is the it red shift, do not
exclude the presence of some source of opacity with a high degree of statistical con dence.