First Galaxies with James Webb Space Telescope

Astract:

The cosmic dark ages - when the Universe was filled with neutral hydrogen that was opaque to ultraviolet light - are thought to have ended around 500 million years after the Big Bang, when first light sources produced enough energetic photons to ionize the neutral hydrogen. This phase is referred to as the epoch of reionization and is also the era of the first galaxies' formation. However, this is also one of the least understood epochs in the Universe's evolution.  James Webb Space Telescope is revolutionizing this field. Observations of clusters of galaxies, when used as cosmic telescopes, can further simplify the task of studying and finding normal galaxies at high redshifts. I will present results from the largest such survey CANUCS which identified new puzzles of star formation at z~7 and beyond.