http://arxiv.org/abs/1908.03324
Recent low-redshift observations give value of the present-time Hubble parameter $H_{0}\simeq 74~\rm{km}/{sec}/\rm{Mpc}$, roughly 10\% higher than the predicted value $H_{0}=67.4~\rm{km}/{sec}/\rm{Mpc}$ from Planck’s observations of the CMB and the $\Lambda$CDM model. Phenomenologically, we show that the Friedmann equation requires an extra unknown component $X$ to contribute a negative density to the Universe in order to resolve the Hubble tension without changing the Planck’s constraint on the matter and dark energy densities. For the extra negative density to be sufficiently small, its equation-of-state parameter must satisfy $1/3\leq w_{X}\leq1$. We propose a quintom model of two scalar fields that realizes this condition and successfully resolve the Hubble tension. One scalar field acts as a quintessence while another “phantom” scalar conformally couples to matter in such a way that viable cosmological scenario can be achieved. The model depends only on two parameters, $\lambda_{\phi}$ and $\delta$ which represent rolling tendency of the self-interacting potential of the quintessence and the strength of conformal phantom-matter coupling respectively.
S. Panpanich, P. Burikham, S. Ponglertsakul, et. al.
Mon, 12 Aug 19
28/42
Comments: 10 pages, 4 figures