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Arxiv: Investigating cosmic strings using large-volume hydrodynamical simulations in the context of JWST's massive UV-bright galaxies Published: 11/29/2024 9:00:00 PM Updated: 11/29/2024 9:00:00 PM

Paper abstract: Recent observations from the James Webb Space Telescope (JWST) have uncoveredan unexpectedly large abundance of massive, UV-bright galaxies at highredshifts z \gtrsim 10, presenting a significant challenge to establishedgalaxy formation models within the standard \LambdaCDM cosmologicalframework. Cosmic strings, predicted by a wide range of particle physicstheories beyond the Standard Model, provide a promising potential explanationfor these observations. They may act as additional gravitational seeds in theearly universe, enhancing the process of high-redshift structure formation,potentially resulting in a more substantial population of massive, efficientlystar-forming galaxies. We numerically investigate this prediction inlarge-volume hydrodynamical simulations using the moving-mesh code AREPO andthe well-tested IllustrisTNG galaxy formation model. We evaluate the simulationresults in the context of recent JWST data and find that sufficiently energeticcosmic strings produce UV luminosity and stellar mass functions that are inslightly to substantially better agreement with observations at high redshifts.Moreover, we observe that the halos seeded by cosmic strings exhibit a greaterefficiency of star formation and enhanced central concentrations.Interestingly, our findings indicate that the simulations incorporating cosmicstrings converge with those from a baseline \LambdaCDM model by redshift z~ 6. This convergence suggests that the modified cosmological frameworkeffectively replicates the successful predictions of the standard \LambdaCDMmodel at lower redshifts, where observational constraints are significantlystronger. Our results provide compelling evidence that cosmic strings may playa crucial role in explaining the galaxy properties observed by JWST at highredshifts while maintaining consistency with well-established models at laterepochs.