Growth of Isothermal Perturbations during and after the Recombination ERA

Abstract

A study of the evolution of isothermal is given during and after the recombination era. Effects due to recombination, nonlinear growth and the decoupling of matter and radiation are taken into account. A result of particular interest is that isothermal fluctuations of mass very much smaller than mass at the 5 beginning of the recombination era (i.e. M ≪M_j ≃ 10^5 M⊙) are not damped to extinction. In particular, isothermal fluctuations of mass 25-200 M⊙ survive. The results thus indicate that massive Population III stars in the mass range 25-200 M⊙ need not have formed by fragmentation from massive clouds, but could have formed from perturbations which survived directly from the recombination era.