The Ages of the Oldest Astrophysical Objects in an Ellipsoidal Universe
arxiv(2024)
摘要
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 ΛCDM model. This so-called “impossibly early galaxy problem”
requires too rapid star formation in the earliest galaxies than appears to be
permitted by the ΛCDM 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 ΛCDM model. In this work
we are going to discuss how the recently proposed γδCDM model might
ease and perhaps resolve the time-compression problem. In the γδCDM
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 γδCDM 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 γδCDM 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.
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