Beasts in the Bubbles: Discovering the origins of the first massive galaxies with JWST

Recent observations of the early universe have suggested the impossible: an abundance of ultra-massive, dead galaxies already within 1.5 billion years after the big bang. These ‘cosmic beasts’ must have been among the first galaxies to form, assembling their mass in a luminous burst of star-formation – releasing enough energy to reionize ‘bubbles’ of intergalactic hydrogen < 500 Myr after the Big Bang. Yet, their existence challenges contemporary models of galaxy formation. I will utilize the first observations with JWST to identify their star-forming progenitors, characterize their properties, assess their contribution to reionization, and critically test models of galaxy formation. My Cycle 1 program to observe five massive z ∼ 9 beasts is uniquely suited to the task, and will provide insight into the formation of the first massive galaxies to light up the cosmos.