Accelerated quenching and chemical enhancement of massive galaxies in a $z\sim4$ gas-rich halo

Understand

Stars in galaxies form when baryons radiatively cool down and fall into gravitational wells whose mass is dominated by dark matter.

• Eventually, star formation quenches as gas is depleted and/or perturbed by feedback processes, no longer being able to collapse and condense.
• We report the first spatially resolved spectroscopic observations, using the JWST/NIRSpec IFU, of a massive, completely quiescent galaxy (Jekyll) and its neighborhood at $z=3.714$, when the Universe age was 10% of today's.
• Jekyll resides in a massive dark matter halo (with mass M$_\mathrm{DM}>10^{12}$ M$_\odot$) and forms a galaxy pair with Hyde, which shows very intense dust-enshrouded star formation (star formation rate $\sim300$ M$_\odot$yr$^{-1}$).