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A rapid transition of the dark energy equation of state parameter w at a transition redshift zt < 0.1 from w −1 at z > zt to w < −1 at z < zt can lead to a higher value of the Hubble constant while closely mimicking a Planck18/ΛCDM form of the comoving distance r(z)for z > zt. Such a Late w Phantom Transition (LwP T ) 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 zt = 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 (e.g. Virgo structures). The LwP T 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.

We use an up-to-date compilation of Tully–Fisher data to search for transitions in the evolution of the Tully–Fisher relation. Using an up-to-date data compilation, we find hints at ≈3σ level for a transition at critical distances Dc≃9 Mpc and Dc≃17 Mpc. We split the full sample in two subsamples, according to the measured galaxy distance with respect to splitting distance Dc, and identify the likelihood of the best-fit slope and intercept of one sample with respect to the best-fit corresponding values of the other sample. For Dc≃9 Mpc and Dc≃17 Mpc, we find a tension between the two subsamples at a level of Δχ2>17(3.5σ). Using Monte Carlo simulations, we demonstrate that this result is robust with respect to random statistical and systematic variations of the galactic distances and is unlikely in the context of a homogeneous dataset constructed using the Tully–Fisher relation. If the tension is interpreted as being due to a gravitational strength transition, it would imply a shift in the effective gravitational constant to lower values for distances larger than Dc by ΔGG≃−0.1. Such a shift is of the anticipated sign and magnitude but at a somewhat lower distance (redshift) than the gravitational transition recently proposed to address the Hubble and growth tensions (ΔGG≃−0.1 at the transition redshift of zt≲0.01 (Dc≲40 Mpc)).

Many late time approaches for the solution of the Hubble tension use late time smooth deformations of the Hubble expansion rate H(z) of the Planck18/ΛCDM best fit to match the locally measured value of H0 while effectively keeping the comoving distance to the last scattering surface and Ω0mh2 fixed to maintain consistency with Planck CMB measurements. A well known problem of these approaches is that they worsen the fit to low z distance probes. Here we show that another problem of these approaches is that they worsen the level of the Ω0m − σ8 growth tension. We use the generic class of CPL parametrizations corresponding to evolving dark energy equation of state parameter $w(z)=w_0+w_1\frac{z}{1+z}$ with local measurements H0 prior and identify the pairs (w0, w1) that satisfy this condition. This is a generic class of smooth deformations of H(z) that are designed to address the Hubble tension. We show that for these models the growth tension between dynamical probe data and CMB constraints is worse than the corresponding tension of the standard Planck18/ΛCDM model. We justify this feature using a full numerical solution of the growth equation and fit to the data, as well as by using an approximate analytic approach. The problem does not affect recent proposed solutions of the Hubble crisis involving a SnIa intrinsic luminosity transition at zt ≃ 0.01.