2025/07/03 by Martínez-García, Eric E.
#Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2507.03075
Recent studies have reported a non evolution of galaxy ages at redshifts higher than z∼ 2.5, as well as galaxies older than the Universe. In this work, a sample of galaxies from JWST and HST was analysed via photometry to further understand this astronomical phenomenon. No prior cosmological parameters were assumed in the analysis, but the spectroscopic redshift. When compared to stellar population synthesis models, the results for mass-weighted galaxy ages indicate that the analysed objects seem to be divided into two subsets. The results for the subset with the majority of objects (60% assuming a flat-ΛCDM cosmology) indicate an evolution of galaxy ages within the redshift range z=0.1-7.0, in the sense that higher redshift galaxies are younger than the Universe. Sources of systematic errors were discussed drawing into conclusion that degeneracies between reddening-age-metallicity, and/or AGN emission may explain the rest 40% of the galaxies with ages older than expected from a flat-ΛCDM cosmology.