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Arxiv: Population synthesis and astrophysical inference for high-z JWST galaxies Published: 10/15/2024 6:18:46 PM Updated: 10/15/2024 6:18:46 PM

Paper abstract: Observations of the high-z Universe from JWST have revealed a newpopulation of bright, early galaxies. A robust statistical interpretation ofthis data requires fast forward models that account for uncertainties in galaxyevolution and incorporate observational systematic effects. We present aprobabilistic framework for population synthesis of high-z galaxies andinference of their properties. Our framework is based on the semi-analyticgalaxy-formation model Galacticus. To infer the astrophysical parametersgoverning high-z galaxy evolution, we analyze JWST data from the CEERS andNGDEEP surveys and calculate the likelihood of observing individual objects inapparent magnitude--redshift space, for z>=8.5 galaxy candidates. Weinclude observational selection effects due to limited survey volume and depth,as well as photometric redshift uncertainties. We recover the posteriorprobability distribution for parameters describing star formation and outflowrates. We place an upper limit on the star formation timescale of500~\mathrm{Myr} at a disk velocity of 50~\mathrm{km\ s}^{-1}, and we infera characteristic velocity at which the outflow mass-loading factor is ~ 1of 150^{+280}_{-60}~\mathrm{km\ s}^{-1}, both at 95\% confidence.Marginalizing over our astrophysical model, we find that galaxies in CEERS andNGDEEP data occupy halos with virial masses 10^{10\pm 0.5}~M_{\mathrm{\odot}}at 8.5<= z<= 12, at 95\% confidence. The star formation timescalepreferred by our fit is relatively short compared to typical values at lowerredshifts, consistent with previous findings. The modeling and analysisframework presented here can enable systematic tests of high-z galaxies' dustcontent, initial mass functions, and star formation burstiness in the future.