http://arxiv.org/abs/2012.13932
A rapid transition of the dark energy equation of state parameter $w$ at a transition redshift $z_t<0.1$ from $w\simeq -1$ at $z>z_t$ to $w<-1$ at $z<z_t$ can lead to a higher value of the Hubble constant while closely mimicking a Planck18/$\Lambda$CDM form of the comoving distance $r(z)=\int_0^z\frac{dz’}{H(z’)}$ for $z>z_t$. Such a Late $w$ Phantom Transition ($LwPT$) avoids the discontinuity of $H(z)$ suggested in previous studies and thus does not require a step in the Pantheon Hubble diagram which is strongly constrained. We demonstrate that such an ultra low $z$ abrupt feature of $w(z)$ provides a better fit to cosmological data compared to smooth late time deformations of $H(z)$ that also address the Hubble tension. The strongly present day phantom dark energy behavior implied by this class of models hints towards a rapid approach of a Big Rip singularity which for $z_t=0.02$ will rip the universe in less than 3.5 billion years. Early hints of such effect may be observable in the dynamics of the nearest and largest bound systems ({\it e.g.} Virgo structures). The $LwPT$ can be generically induced by a phantom scalar field frozen by Hubble friction mimicking the cosmological constant and currently entering its ghost instability phase as Hubble friction decreases below the field dynamical scale.
G. Alestas, L. Kazantzidis and L. Perivolaropoulos
Tue, 29 Dec 20
33/66
Comments: 11 pages, 5 Figures. The Mathematica files used for the construction of the figures may me downloaded from this https URL
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