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Astron. Astrophys. 324, 27-31 (1997)

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1. Introduction

The Big Bang model of the Universe's evolution is now the preferred one, after the success of the COBE mission. Strong evidence against alternative models is provided by COBE-FIRAS (Mather et al., 1990) and recent COBRA (Gush et al., 1990) results. Their spectral measurements of the CBR have set stringent upper limits on any spectral deviations from a pure Plankian curve. This means that there was no substantial energy emission after the epoch of annihilation of the electrons and positrons at redshift [FORMULA] as well as the latest reionization ([FORMULA]). So, we are led to the conclusion that the appropriate scenario for the evolution of the Universe may be the simplest one, and the pure Big Bang model should be used as the standard. The COBE mission provides us with the answer to one of the most fundamental questions - were do we live? - we live in an expanding Universe with a Big Bang at the beginning!

This conclusion is confirmed by the results of measurements of the spatial fluctuations of CBR temperature in the other part of the COBE program. Some evidence in favor of a Zel'dovich - Harrison spectrum of primordial large-scale structure is apparent in the spatial fluctuations and this should be kept in mind for future considerations.

So, now we can try to investigate the next level of observational effects which are provided by proto-objects in the post recombination epoch. One of the most probable classes of such effects will be considered here. They are the so-called SSF - Spectral Spatial Fluctuations (Dubrovich, 1994). Actually, they are the proto-objects at high redshift - 10 [FORMULA] z [FORMULA] 300, which must contain some amount of molecules and which have a peculiar velocity [FORMULA] relative to the CBR. There are necessary and sufficient conditions for the SSF to be produced. The theory of this process was discussed by Dubrovich (1977, 1983, 1994) and by Maoli et al. (1994). Some experiments were described by De Bernardis (1992) and some plans by Signore et al.(1993).

All this work is based on the simplest mechanism of the SSF formation - pure reflection of the CBR photons due to the opacity of a proto-object in narrow spectral lines and the Doppler shift in frequency due to its peculiar velocity. In this paper another mechanism will be considered.

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© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998