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Free keywords:
STAR-FORMING GALAXIES; SPACE-TELESCOPE OBSERVATIONS; 1ST BILLION YEARS;
LYMAN-ALPHA; COSMIC REIONIZATION; LUMINOSITY FUNCTION; IONIZED BUBBLE;
ACCELERATED REIONIZATION; HYDROGEN REIONIZATION; PHOTOMETRIC REDSHIFTSAstronomy & Astrophysics;
Abstract:
We present the first results from the Web Epoch of Reionization Ly alpha Survey (WERLS), a spectroscopic survey of Ly alpha emission using Keck I/MOSFIRE and LRIS. WERLS targets bright (J < 26) galaxy candidates with photometric redshifts of 5.5 less than or similar to z less than or similar to 8 selected from pre-JWST imaging embedded in the Epoch of Reionization (EoR) within three JWST deep fields: CEERS, PRIMER, and COSMOS-Web. Here, we report 11 z similar to 7-8 Ly alpha emitters (LAEs; three secure and eight tentative candidates) detected in the first five nights of WERLS MOSFIRE data. We estimate our observed LAE yield is similar to 13%, which is broadly consistent with expectations assuming some loss from redshift uncertainty, contamination from sky OH lines, and that the Universe is approximately half-ionized at this epoch, whereby observable Ly alpha emission is unlikely for galaxies embedded in a neutral intergalactic medium. Our targets are selected to be UV-bright, and span a range of absolute UV magnitudes with -23.1 < M (UV) < -19.8. With two LAEs detected at z = 7.68, we also consider the possibility of an ionized bubble at this redshift. Future synergistic Keck+JWST efforts will provide a powerful tool for pinpointing beacons of reionization and mapping the large-scale distribution of mass relative to the ionization state of the Universe.
