3:30–4:30 pm ERC 161
Alan Dressler (Carnegie Institution for Science) "Star Formation Histories of the First Galaxies -- Starbursts Rule!"
An important JWST mission is to observe and understand the buildup of stellar mass in the first galaxies. I describe a study (arXiv:2306.02469) of galaxy star formation histories (SFHs) in the first billion years, derived from spectral energy distributions (SEDs) of ~900 galaxies with deep NIRCam imaging. A new code, SEDz*, that assembles A-star templates to match observed SEDs confirms early JWST-ERO results distinguishing four SFH types: burst, stochastic, `contiguous,’ and `continuous.' Remarkably, single-and-multiple epoch starbursts -- with stellar masses of 10^8 -- 10^9 Msun -- describe ~70% of the sample, playing the lead role in this critical period of cosmic history. Bursts of this intensity have not been anticipated, so this and similar studies should provide strong constraints for theoretical modeling of the initial growth of the first galaxies.
