Speaker
Description
In this talk, I will present UV continuum properties from the EPOCHS sample of 1011 high-redshift galaxies spanning z=6.5-13 across 179 square arcmin of public and PEARLS GTO NIRCam imaging from JWST Cycle 1. I will show the bias corrected UV beta-MUV relation, from which I find that the MUV=-19 galaxy population becomes extremely blue at z>11. We find that 68 of these candidates are robust ultra-blue galaxies with beta<-2.8. Performing Bayesian SED fitting on the candidates shows that, as expected, they host non-zero Lyman continuum escape fractions and hence may be important contributors to the reionization of the Universe at early times. I show that these extremely blue systems could be due to the presence of strong Lyman alpha emission (e.g. Saxena+23), which can bias beta by as much as 0.6 bluewards. This would imply large ionized bubble sizes at these epochs, which has been seen in early spectroscopic results with JWST. In addition, I find a large population of z=6.5-11 low mass, red galaxies not seen in HST studies, which could be due to damped Lyman alpha systems or the Lyman alpha damping wing, both of which bias beta red in NIRCam wideband surveys. Finally, I find that our observed average beta values at z=11-13 are consistent with the theoretical models of Pop. III stars from Zackrisson+11 mixed with more-metal enriched systems, although several degeneracies exist here highlighting the importance of NIRSpec spectroscopic data for these sources.
