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Abstract: We compare perturbations in a fluid model of dark energy with those in ascalar field. As compared to the $\Lambda$CDM model, large scale matter powerspectrum is suppressed in fluid model as well as in a generic quintessence darkenergy model.To check the efficacy of fluid description of dark energy inemulating a scalar field, we consider a potential which gives the samebackground evolution as a fluid with a constant equation of state. We show thatfor sub-Hubble scales, a fluid model effectively emulates a scalar field model.At larger scales, where dark energy perturbations may play a significant role,the fluid analogy breaks down and the evolution of matter density contrastdepends on individual scalar field models.



Author: H. K. Jassal

Source: https://arxiv.org/







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