We present a comparison of the nitrogen-to-oxygen ratio (N/O) in 37high-redshift galaxies at $z\sim$2 taken from the KMOS Lensed Emission Linesand VElocity Review (KLEVER) Survey with a comparison sample of local galaxies,taken from the Sloan Digital Sky Survey (SDSS). The KLEVER sample shows only amild enrichment in N/O of $+$0.1 dex when compared to local galaxies at a givengas-phase metallicity (O/H), but shows a depletion in N/O of $-$0.36 dex whencompared at a fixed stellar mass (M$_*$). We find a strong anti-correlation inlocal galaxies between N/O and SFR in the M$_*$-N/O plane, similar to theanti-correlation between O/H and SFR found in the mass-metallicity relation(MZR). We use this anti-correlation to construct a fundamental nitrogenrelation (FNR), analogous to the fundamental metallicity relation (FMR). Wefind that KLEVER galaxies are consistent with both the FMR and the FNR. Thissuggests that the depletion of N/O in high-$z$ galaxies when considered at afixed M$_*$ is driven by the redshift-evolution of the mass-metallicityrelation in combination with a near redshift-invariant N/O-O/H relation.Furthermore, the existence of an fundamental nitrogen relation suggests thatthe mechanisms governing the fundamental metallicity relation must be probed bynot only O/H, but also N/O, suggesting pure-pristine gas inflows are not theprimary driver of the FMR, and other properties such as variations in galaxyage and star formation efficiency must be important.
The KLEVER survey: Nitrogen abundances at z ∼ 2 and probing the existence of a fundamental nitrogen relation
MERCURIO AMATA;
2022
Abstract
We present a comparison of the nitrogen-to-oxygen ratio (N/O) in 37high-redshift galaxies at $z\sim$2 taken from the KMOS Lensed Emission Linesand VElocity Review (KLEVER) Survey with a comparison sample of local galaxies,taken from the Sloan Digital Sky Survey (SDSS). The KLEVER sample shows only amild enrichment in N/O of $+$0.1 dex when compared to local galaxies at a givengas-phase metallicity (O/H), but shows a depletion in N/O of $-$0.36 dex whencompared at a fixed stellar mass (M$_*$). We find a strong anti-correlation inlocal galaxies between N/O and SFR in the M$_*$-N/O plane, similar to theanti-correlation between O/H and SFR found in the mass-metallicity relation(MZR). We use this anti-correlation to construct a fundamental nitrogenrelation (FNR), analogous to the fundamental metallicity relation (FMR). Wefind that KLEVER galaxies are consistent with both the FMR and the FNR. Thissuggests that the depletion of N/O in high-$z$ galaxies when considered at afixed M$_*$ is driven by the redshift-evolution of the mass-metallicityrelation in combination with a near redshift-invariant N/O-O/H relation.Furthermore, the existence of an fundamental nitrogen relation suggests thatthe mechanisms governing the fundamental metallicity relation must be probed bynot only O/H, but also N/O, suggesting pure-pristine gas inflows are not theprimary driver of the FMR, and other properties such as variations in galaxyage and star formation efficiency must be important.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.