A comprehensive metallicity analysis of J0332-3557: establishing a z ~ 4 anchor for direct gas metallicity and C/O abundance investigations

Understand

We provide one of the most comprehensive metallicity studies at z $\sim$ 4 by analyzing the UV/optical HST photometry, and rest-frame VLT-FORS2 ultraviolet and VLT-XSHOOTER optical spectra of J0332-3557, a gravitationally lensed galaxy magnified by a factor of 20.

• With a 5$\sigma$ detection of the auroral O III]1666 line, we are able to derive a direct gas metallicity estimate for our target.
• We find Z_gas = 12 + log(O/H) = 8.26 $\pm$ 0.06, which is compatible with an increasing of both the gas fraction and the outflow metal loading factor from z $\sim$ 0 to z $\sim$ 4.
• J0332-3557 is the most metal-rich individual galaxy at z $\sim$ 4 for which the C/O ratio has been measured.