Is the cosmological dark sector better modeled by a generalized Chaplygin gas or by a scalar field?
Sergio del Campo (Instituto de Física, Pontificia Universidad Católica de Valparaíso, 0000 0001 1537 5962, Avenida Brasil 2950, Casilla 4059, Valparaiso, Chile); Júlio C. Fabris (National Research Nuclear University “MEPhI”, 0000 0000 8868 5198, Kashirskoe sh. 31, 115409, Moscow, Russia, Departamento de Física, Universidade Federal do Espírito Santo, 0000 0001 2167 4168, Av. Fernando Ferrari, 514, Campus de Goiabeiras, CEP 29075-910, Vitória, Espírito Santo, Brazil); Ramón Herrera (Instituto de Física, Pontificia Universidad Católica de Valparaíso, 0000 0001 1537 5962, Avenida Brasil 2950, Casilla 4059, Valparaiso, Chile); Winfried Zimdahl (Departamento de Física, Universidade Federal do Espírito Santo, 0000 0001 2167 4168, Av. Fernando Ferrari, 514, Campus de Goiabeiras, CEP 29075-910, Vitória, Espírito Santo, Brazil)
Both scalar fields and (generalized) Chaplygin gases have been widely used separately to characterize the dark sector of the universe. Here we investigate the cosmological background dynamics for a mixture of both these components and quantify the fractional abundances that are admitted by observational data from supernovae of type Ia and from the evolution of the Hubble rate. Moreover, we study how the growth rate of (baryonic) matter perturbations is affected by the dark-sector perturbations.
