2019/06/30 by Xiaolei Li, Arman Shafieloo · 2 citations
Physics and Astronomy · #astro-ph.CO #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.3847/2041-8213/ab3e09
published as The Astrophysical Journal Letters (2019), 883(1), L3 · 7 pages, 4 figures, 1 table, published in ApJL
arxiv created 2020/01/12 · arxiv updated 2020/01/14
Motivated by the current status of the cosmological observations and significant tensions in the estimated values of some key parameters assuming the standard ΛCDM model, we propose a simple but radical phenomenological emergent dark energy model where dark energy has no effective presence in the past and emerges at the later times. Theoretically, in this phenomenological dark energy model with zero degree of freedom (similar to a ΛCDM model), one can derive that the equation of state of dark energy increases from -\frac23 \rmln 10 -1 in the past to -1 in the future. We show that by setting a hard-cut 2σ lower bound prior for the H0 that associates with 97.72% probability from the recent local observations~\citepriess2019large, this model can satisfy different combinations of cosmological observations at low and high redshifts (SNe Ia, BAO, Lyα BAO and CMB) substantially better than the concordance ΛCDM model with Δχ2bf ∼ -41.08 and Δ \rmDIC ∼-35.38. If there are no substantial systematics in SN Ia, BAO or Planck CMB data and assuming reliability of the current local H0 measurements, there is a very high probability that with slightly more precise measurement of the Hubble constant our proposed phenomenological model rules out the cosmological constant with decisive statistical significance and is a strong alternative to explain combination of different cosmological observations. This simple phenomenologically emergent dark energy model can guide theoretically motivated dark energy model building activities.