Abstract
In the standard cosmological framework, the Hubble diagram is interpreted by
assuming that the light emitted by standard candles propagates in a spatially
homogeneous and isotropic spacetime. However, the light from "point sources" --
such as supernovae -- probes the universe on scales where the homogeneity
principle is no longer valid. Inhomogeneities are expected to induce a bias and
a dispersion of the Hubble diagram. This is investigated by considering a
Swiss-cheese cosmological model, which (1) is an exact solution of the Einstein
field equations, (2) is strongly inhomogeneous on small scales, but (3) has the
same expansion history as a strictly homogeneous and isotropic universe. By
simulating Hubble diagrams in such models, we quantify the influence of
inhomogeneities on the measurement of the cosmological parameters. Though
significant in general, the effects reduce drastically for a universe dominated
by the cosmological constant.
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