Finding Peas in the Early Universe with JWST

Understand

The Early Release Observations (EROs) of JWST beautifully demonstrate the promise of JWST in characterizing the universe at cosmic dawn.

• We analyze the ERO spectra of three $z \sim 8$ galaxies to determine their metallicities, gas temperatures and ionization.
• These galaxies offer the first opportunity to understand the physical properties of epoch-of-reionization galaxies through detailed rest-optical emission line spectroscopy.
• We show that these objects have metal abundances $12+\log[O/H] \approx 6.9 - 8.2$, based on both the $T_e$ method and on a recent calibration of the $R_{23}$ metallicity indicator.