The Fast and Furious in JWST high-$z$ galaxies

Recent JWST surveys reveal a striking abundance of massive galaxies at cosmic dawn, earlier than predicted by $\mathrm{\Lambda }$CDM. The implied speed-up in galaxy formation by gravitational collapse is reminiscent of short-period galaxy dynamics described by the baryonic Tully-Fisher relation. This may originate in weak gravitation tracking the de Sitter scale of acceleration $a_{dS}=cH$, where $c$ is the velocity of light and $H(z)\propto {(1+z)}^{3\mathrm{/}2}$ is the Hubble parameter with redshift $z$. With no free parameters, this produces a speed-up in early galaxy formation by an order of magnitude with essentially no change in initial galaxy mass function. It predicts a deceleration parameter $q_0=1-{\left(2\pi \mathrm{/}GA{a}_{dS}\right)}^2=-0.98\pm 0.5$, where $G$ is Newton’s constant and $A=(47\pm 6)M_{\odot }$,(km/s)${}^{-4}$ is the baryonic Tully-Fisher coefficient (McGaugh 2012). At $3\sigma$ significance, it identifies dynamical dark energy alleviating $H_0$-tension when combined with independent $q_0$ estimates in the Local Distance Ladder. Conclusive determination of $q_0=d\log (\theta (z)H(z))\mathrm{/}dz\mid {}_{z=0}$ is expected from BAO angle $\theta (z)$ observations by the recently launched {\em Euclid} mission.