Metal deficiency in cluster star-forming galaxies at z=2

Understand

We investigate the environmental effect on the metal enrichment of star-forming galaxies (SFGs) in the farthest spectroscopically confirmed and X-ray detected cluster, CL~J1449+0856 at $z=1.99$.

• We combined HST/WFC3~G141 slitless spectroscopic data, our 13-band photometry, and a recent Subaru/MOIRCS near infrared spectroscopic follow-up to constrain the physical properties of SFGs in CL~J1449+0856 and in a mass-matched field sample.
• After a conservative active galactic nuclei (AGN) removal, stacking individual MOIRCS spectra of $6$ ($31$) sources in the cluster (field) in the mass range $10 \leq \mathrm{log(M/M_{\odot}}) \leq 11$, we find a $\sim4\sigma$ significant lower [N II]/H$\alpha$ ratio in the cluster than in the field.
• Stacking a subsample of $16$ field galaxies with H$\beta$ and [O III] in the observed range, we measure a [O III]/H$\beta$ ratio fully compatible with the cluster value.