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Harvard ADS: The ages of the oldest astrophysical objects in an ellipsoidal universe

Paper abstract: James Webb Space Telescope's (JWST) observations since its launch have shown us that there could be very massive and very large galaxies, as well as massive quasars very early in the history of the Universe, conflicting expectations of the ?CDM model. This so-called "impossibly early galaxy problem" requires too rapid star formation in the earliest galaxies than appears to be permitted by the ?CDM model. In fact, this might not be a high masses problem, but a "time-compression problem": time too short for the observed large and massive structures to form from the initial seeds. A cosmological model that could allocate more time for the earliest large structures to form would be more conforming to the data than the ?CDM model. In this work we are going to discuss how the recently proposed ?dCDM model might ease and perhaps resolve the time-compression problem. In the ?dCDM model, different energy densities contribute to the Hubble parameter with different weights. Additionally, in the formula for the Hubble parameter, energy densities depend on the redshift differently than what their physical nature dictates. This new way of relating Universe's energy content to the Hubble parameter leads to a modified relation between cosmic time and redshift. We test the observational relevance of the ?dCDM model to the age problem by constraining its parameters with the ages of the oldest astronomical objects (OAO) together with the cosmic chronometers (CC) Hubble data and the Pantheon+ Type Ia supernovae data of the late Universe at low redshift. We find that, thanks to a modified time-redshift relation, the ?dCDM model has a more plausible time period at high redshift for large and massive galaxies and massive quasars to form, whereas the age of the Universe today is not modified significantly.