Affiliation: Instituto de Astrofísica e Ciências do Espaço – CAUP

Contribution: Oral

Title: Unveiling LAE growth with HST and JWST

Abstract: The James Webb Space Telescope (JWST) has unveiled a new window into the rest-frame optical light emitted from early-universe galaxies, offering a perfect complement to prior Hubble Space Telescope (HST) observations and furnishing a comprehensive perspective on galaxy evolution in the early cosmos. Here we present a comparative analysis of Lyman-alpha emitter (LAE) sizes, harnessing the capabilities of both HST and JWST. Our dataset, sourced from the full COSMOS field, comprised ~500 LAEs analysed through HST observations, highlighting their consistent compactness with average sizes of around 1 kpc (Paulino-Afonso et al., 2018). Additionally, we observe that LAEs with higher rest-frame equivalent widths tend to be more compact, suggesting a correlation between intense emission and high star-formation rate densities. The integration of recent JWST data (COSMOS-Webb, PI: J. Kartaltepe & C. Casey and PRIMER, PI: J.Dunlop) enables a broad-spectrum analysis of the size evolution of LAEs from redshift z~2 to z~6. By synthesising observations from both telescopes, our research confirms the compact nature of LAEs across both UV and optical rest-frames at z>4 (cf. also Ono et al. 2024). However, at z<4 the LAE optical rest-frame sizes can be up to two times bigger than their UV rest-frame counterparts (Paulino-Afonso et al., in prep.) This approach underscores the importance of multi-wavelength studies in unravelling the complexities of galaxy formation. Are LAE sources indicative of the initial phase in the early galactic formation, or are they tracers of star-forming clumps? This is the question we aim to answer by showing how our morphological analysis can be complemented with pixel-by-pixel SED fitting.

This contribution can be found here (pdf).