Chapter III Formation of Proto-Galaxies in the Expanding Universe : Gravitational instability

概要

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In this report the recent investigations carried out mainly in Japan concerning the problems of gravitational instability and galaxy formation in the expanding universe are summarized. Firstly the problem of gravitational instability is dealt with. The linear theory is formulated in the Lagrangian reference system and is developed also in the case of the Brans-Dicke cosmology. Thereafter the non-linear behaviors of various perturbations are treated, partly by extending Lifshitz's linear theory to the second order and partly by taking into account the full non-linearity in the sense of Newtonian hydrodynamics in the expanding universe. Next we turn to the problem of galaxy formation. As for an initial state of the universe the existence of primordial turbulence is assumed and whether density perturbations can be raised by the turbulent motions at the stage t≲t_D (the decoupling epoch) is examined. Thereafter we look into the formation of a gravitationally bound system and its passage to the contraction phase, dividing the stage t&rsim;t_D into the three stages, i. e., the early stage (an expansion phase), the middle stage (the separation from general expansion and the subsequent contraction) and the later stage (dynamical processes of a supermassive object).
理論物理学刊行会の論文
1972-02-29