Type Ia supernovae discoveries at high redshifts (z > 1) support past deceleration (Riess et al. 2001). This past deceleration has also been confirmed using quasars (z ≈ 6) (Risaliti and Lusso 2015) as well as gamma-ray bursts (z ≈ 9) (Demianski et al. 2017).
According to Davis and Lineweaver (2004), “Recession velocities exceed the speed of light in all viable cosmological models for objects with redshifts greater than z ~ 1.5”. In fact, in the ΛCDM concordance model itself, all galaxies beyond a redshift of z = 1.46 are receding faster than the speed of light (Davis and Lineweaver 2004).
Therefore, my question is, how can every superluminal remote expansion (z = 1.7 (SN Ia), z = 6 (QSO), z = 9 (GRB)) be justified as “slowing down” under the gravitational influence of matter as compared to subluminal local expansion (z = 0.01 (SN Ia))?
Isn’t this is a paradox?
I would like to add some additional details to the above question as it still appears paradoxical when discoveries at high redshifts are taken as an indication of "slowing down" particularly when those redshifts are interpreted in terms of recession velocities.
Take for instance the following plot by the High-Z Supernova Search Team; the researchers have clearly interpreted redshifts in terms of recession velocities.
According to this plot, local recession velocities (just 1% of speed of light; z = 0.01) indicate a faster rate of expansion (acceleration) as compared to remote recession velocities (60% of speed of light; z = 0.6) that indicate a slower rate of expansion (deceleration) - a clear-cut paradox.
Here is an excerpt that shows recession velocities from observed redshifts do play a role in determining the expansion rate, “It has been noted by Zehavi et al. (1998) that the SNe Ia out to 7000 km/s (108 Mpc) exhibit an expansion rate (65 km/s/Mpc) that is 6% greater than that measured for the more distant objects” (Riess et al. 1998). It becomes obvious that redshifts of the more distant objects might have also been interpreted in terms of recession velocities to compare the expansion rates.
Moreover, significant time dilation is observed at high redshifts than at low redshifts. Now, time dilation is based on the fact that a moving clock ticks slowly as compared to a stationary one, that is, an event on a "receding" emitter appears time dilated. The fact that there is significant time dilation at high redshifts than at low redshifts suggests that the expansion at high redshifts (z > 1) is definitely not a feeble expansion as compared to the expansion at low redshift (z = 0.01) which is as good as "almost stationary".