Speaker
Description
Early data from the James Webb Space Telescope (JWST) has uncovered the
existence of a surprisingly abundant population of very massive galaxies at extremely high
redshift, which are hard to accommodate within the standard ΛCDM cosmology. We explore
whether the JWST observations may be pointing towards more complex dynamics in the dark
energy (DE) sector. Motivated by the ubiquity of anti-de Sitter vacua in string theory, we
consider a string-inspired scenario where the DE sector consists of a negative cosmological
constant (nCC) and a evolving component with positive energy density on top, whose equation
of state is allowed to cross the phantom divide. We show that such a scenario can drastically
alter the growth of structure compared to ΛCDM, and accommodate the otherwise puzzling
JWST observations if the dynamical component evolves from the quintessence-like regime
in the past to the phantom regime today: in particular, we demonstrate that the presence
of a nCC (which requires a higher density for the evolving component) plays a crucial role
in enhancing the predicted cumulative comoving stellar mass density. Our work reinforces
the enormous potential held by observations of the abundance of high-z galaxies in probing
cosmological models and new fundamental physics, including string-inspired ingredients.
| eijupala@gmail.com, rs.umukhopadhyay@jmi.ac.in | |
| Affiliation | Centre for Theoretical Physics, Jamia Millia Islamia, New Delhi-110025, India |
