One remarkable patch of sky just solved a major cosmic puzzle.
Shortly after the Big Bang — before any stars arose — the first stable, neutral atoms formed.
These atoms, however, absorb visible light, rendering space opaque.
Energetic, ultraviolet photons are required to reionize atoms.
Determining how early stars and galaxies reionized the Universe is a cosmic challenge.
It’s a challenge perfectly suited for JWST, however, with help from Einstein.
This image shows Pandora’s cluster, Abell 2744: a massive collection of galaxy clusters.
This huge mass collection bends and distorts the surrounding spacetime.
Background objects, through gravitational lensing, appear magnified and stretched.
This reveals galaxies too small, faint, and distant to otherwise be glimpsed.
Ultra-distant, massive galaxies create too little ultraviolet light to explain cosmic reionization.
They account for between 5% and 20% of the needed ionizing photons.
Despite the hopes of some, neither can quasar emissions.
However, gravitational lensing newly revealed eight tiny, faint, distant dwarf galaxies.
With only ~1 million stars apiece, they are ~100 times as common as their bigger, brighter counterparts.
They were caught producing four times as many ionizing photons as previously assumed.
It’s these cosmic dwarfs — not quasars or bright galaxies — that primarily reionize the Universe.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words.