Ancient and Dormant: A Giant Galaxy Discovered at Redshift 4.658.

Astronomers have confirmed the existence of a massive quiescent galaxy, GS-9209, at redshift 4.658, just 1.25 billion years after the Big Bang, using the James Webb Space Telescope (JWST) NIRSpec. The galaxy has a stellar mass of M∗ = 3.8 ± 0.2 × 1010 M⊙, which formed over a ≃ 200 Myr period before quenching its star formation activity at z=6.5. This discovery sheds light on the rapid assembly of the earliest galaxies and the physics of galaxy formation.