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Astron. Astrophys. 348, 25-30 (1999)

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Models of Universe with an inhomogeneous Big Bang singularity

II. CMBR dipole anisotropy as a byproduct of a conic Big-Bang singularity

J. Schneider and M.-N. Célérier

CNRS UPR 176 - Département d'Astrophysique Relativiste et de Cosmologie, Observatoire de Paris-Meudon, 5 place Jules Janssen, F-92195 Meudon Cédex, France

Received 26 June 1998 / Accepted 23 April 1999


The existence of stars and galaxies reqires cosmological models with an inhomogeneous matter and radiation distribution. But in these models the initial singularity surface [FORMULA] is in general homogeneous (independent of r). In this second paper of a series devoted to an inhomogeneous Big Bang singularity, we investigate the cosmic microwave background radiation (CMBR) dipole. A special Tolman-Bondi Universe is used to study the effect of a Big-Bang singularity, depending linearly on r, on the CMBR anisotropy. It is shown that, for an observer located off the "center" of this Universe ([FORMULA]), the parameters of the model can be tuned so as to reproduce, with a good approximation, the dipole and the quadrupole moments of the CMBR anisotropy observed in recent experiments. If the dipole should prove cosmological, a slight delaying of the Big-Bang over spatial coordinates would thus be a good candidate for its interpretation.

Key words: cosmology: cosmic microwave background – cosmology: theory

Send offprint requests to: J. Schneider

Correspondence to: schneider@obspm.fr

© European Southern Observatory (ESO) 1999

Online publication: July 16, 1999