Non-adiabatic Chaplygin gas

作者：Borges H A; Carneiro S^*; Fabris J C; Zimdahl W

来源：Physics Letters B, 2013, 727(1-3): 37-42.

DOI：10.1016/j.physletb.2013.10.032

The split of a generalised Chaplygin gas with an equation of state p = -A/rho(alpha) into an interacting mixture of pressureless matter and a dark-energy component with equation of state p(Lambda) = -rho(Lambda) implies the existence of non-adiabatic pressure perturbations. We demonstrate that the square of the effective (non-adiabatic) sound speed C-s of the medium is proportional to the ratio of the perturbations of the dark energy to those of the dark matter. Since, as demonstrated explicitly for the particular case alpha = -1/2, dark-energy perturbations are negligible compared with dark-matter perturbations on scales that are relevant for structure formation, we find vertical bar C-s(2)vertical bar << 1. Consequently, there are no oscillations or instabilities which have plagued previous adiabatic Chaplygin-gas models.

• 出版日期2013-11