Cosmological interpretation of JWST observations

Observational data from the James Webb Space Telescope (JWST) indicate a significant number of galaxies with redshifts $z > 10$. Galaxies with record-breaking redshifts exhibit luminosities comparable to those of galaxies in the local universe, and they are small in size, measuring hundreds of parsecs, as determined within the standard cosmological model, $\Lambda$CDM. Within this framework, a satisfactory explanation for their formation and evolution has not yet been found. So, most current research focuses on revising theories of galaxy formation and evolution to align with JWST observational data. In this talk, we discuss cosmological tests based on JWST observations, which could provide an alternative explanation. High-redshift galaxies detected by the JWST exhibit brightness and large masses, yet their sizes are over 10 times smaller than those of low-redshift galaxies with comparable masses. This leads to an increase in the gravitational potential $\phi$ and, consequently, an increase in the velocity dispersion, which in turn results in the broadening of galaxy spectral lines, including ${\rm Ly}_\alpha$. Thus, their spectral lines measured by the JWST must be widened. Checking galaxy spectral line widths constitutes a new physical cosmological test, which can be conduct using the current JWST data. The high rate of star formation in those galaxies implies a high number density of ionizing photons. This leads to a significant tension with the optical depth of reionization based on the cosmic microwave background (CMB). The previously known tensions of the $\Lambda$CDM model ($H_0$, $\sigma_8$), along with this new inconsistency, indicate that the method of using CMB to determine cosmological parameters and the concept of Planck precision cosmology may require further evaluation.