THE AMPLIFICATION OF COSMOLOGICAL DENSITY PERTURBATIONS IN THE RECOMBINATION AREA - UPPER LIMITS FOR GALAXY MASSES

Cosmological density perturbations with masses below 10(15)M. are the subject. Their evolution from cosmological times where they are stable (before hydrogen recombination) to times where they are unstable(afte r recombination) is studied. It is found that not the amplification of the density contrasts by pure self-gravity in the unstable phase is d ominant but the amplification duping times of stability just before th e perturbations become unstable. The decoupling of the radiation from the matter perturbations during the recombination plays a crucial role , which leads to a steep drop of the speed of sound. The larger the ma sses are, the smaller the amplification is. Above 10(12)M.-10(13)M. th e amplification is so small that this can be regarded as upper limits for galaxies.