The Webb Epoch of Reionization Lyman-alpha Survey (WERLS)

NASA Key Strategic Mission Support | Keck/MOSFIRE+LRIS | 29N | PI - C. Casey & J. Kartaltepe

We propose the Webb Epoch of Reionization Lyman-alpha Survey (WERLS), a spectroscopic redshift survey using MOSFIRE and LRIS, targeting ~800 galaxies embedded within the Epoch of Reionization (EoR) at 6<z<8. Our goals are to:

1. conduct a census of Ly-alpha emission in already identified luminous EoR galaxies (M_UV< -21) to map ionization bubbles in the intergalactic medium at a time when the Universe was partially ionized and on scales much larger than the expected size of ionization bubbles,
2. directly compare the Ly-alpha-inferred location of ionization bubbles to underlying galaxy density maps that will be measured via deep Webb NIRCam imaging to directly constrain the galaxies responsible for reionization, and
3. increase the number of spectroscopically-confirmed bright EoR sources by a factor of ~2-4x within 6<z<8 via firm detection of Ly-alpha emission, which will critically inform photometric redshift calibration of fainter EoR-era galaxies exclusively detected by Webb. This survey will be conducted in preparation for, and in conjunction with, the largest and deepest extragalactic imaging surveys from the James Webb Space Telescope Cycle 1 and ERS programs covering 0.7deg^2: COSMOS-Webb, PRIMER-UDS, and CEERS. These programs aim to reveal several thousands of EoR galaxies and map their distribution in large scale structure on 10-100Mpc scales. WERLS will focus on already-identified bright galaxies in these surveys, which likely trace the highest mass overdensities to be found by Webb; detection of Lyman-alpha will reveal whether or not they live in ionized bubbles.