Skewness as a test for quartessence

Quartessence is one of the alternatives to ΛCDM that has lately attracted considerable interest. According to this unifying dark matter/energy scenario, the Universe evolved from an early nonrelativistic matter-dominated phase to a more recent accelerated expansion phase, driven by a single fluid component. Recently, it has been shown that some problems of the quartessence model, such as the existence of instabilities and oscillations in the matter power spectrum, can be avoided if a specific type of intrinsic entropy perturbation is considered. In the present article we explore the role of skewness in constraining this nonadiabatic scenario. We show that nonadiabatic quartessence and quintessence have different signatures for the skewness of the density distribution on large scales and suggest that this quantity might prove helpful to break possible degeneracies between them.