[OIII] emission line as a tracer of star-forming galaxies at high redshifts: Comparison between H$\alpha$ and [OIII] emitters at $z$=2.23 in HiZELS

TL;DR

This study compares Hα and [OIII] emission line-selected galaxies at z=2.23, finding similar physical properties and highlighting [OIII] as a valuable tracer for high-redshift star-forming galaxies, especially beyond z>3.

Contribution

It demonstrates that [OIII] emission can effectively trace star-forming galaxies at high redshift, offering an alternative when Hα is unobservable from the ground.

Findings

Hα and [OIII] emitters have similar stellar mass, dust, and SFR distributions.

Sources with strong [OIII] emission show higher star formation activity.

[OIII] is a promising tracer for star-forming galaxies at z>3.

Abstract

We investigate the properties of $z$=2.23 H$\alpha$ and [OIII]$\lambda$5007 emitters using the narrow-band-selected samples obtained from the High-$z$ Emission Line Survey (HiZELS: Sobral et al. 2013). We construct two samples of the H$\alpha$ and [OIII] emitters and compare their integrated physical properties. We find that the distribution of stellar masses, dust extinction, star formation rates (SFRs), and specific SFRs, is not statistically different between the two samples. When we separate the full galaxy sample into three subsamples according to the detections of the H$\alpha$ and/or [OIII] emission lines, most of the sources detected with both H$\alpha$ and [OIII] show ${\rm log(sSFR_{UV})}$$\gtrsim$-9.5. The comparison of the three subsamples suggests that sources with strong [OIII] line emission tend to have the highest star-forming activity out all galaxies that we study. We argue that the [OIII] emission line can be used as a tracer of star-forming galaxies at high redshift, and that it is especially useful to investigate star-forming galaxies at $z$$>$3, for which H$\alpha$ emission is no longer observable from the ground.