Easing Tensions with Quartessence [CEA]

http://arxiv.org/abs/1704.06277


Tensions between cosmic microwave background (CMB) observations and the growth of the large-scale structure (LSS) inferred from late-time probes pose a serious challenge to the concordance $\Lambda$CDM cosmological model. State-of-the-art CMB data from the Planck satellite predicts a higher rate of structure growth than what preferred by low-redshift observables. Such tension has hitherto eluded conclusive explanations in terms of straightforward modifications to $\Lambda$CDM, e.g. the inclusion of massive neutrinos or a dynamical dark energy component. Here, we investigate `quartessence’ models, where a single dark component mimics both dark matter and dark energy. We show that such models greatly alleviate the tension between high and low redshift observations, thanks to the non-vanishing sound speed of quartessence that inhibits structure growth at late times on scales smaller than its corresponding Jeans’ length. In particular, the $3.4\sigma$ tension between CMB and LSS observables is thoroughly reabsorbed. For this reason, we argue that quartessence deserves further investigation and may lead to a deeper understanding of the physics of the dark Universe.

Read this paper on arXiv…

S. Camera, M. Martinelli and D. Bertacca
Mon, 24 Apr 17
17/54

Comments: 7 pages, 5 figures, 1 table; comments are welcome