Nebular line emission from z > 7 galaxies in cosmological simulations: rest-frame UV to Optical lines

TL;DR

This study uses advanced cosmological simulations to predict the detectability of nebular emission lines from galaxies at redshifts greater than 7, highlighting their observability with current and upcoming telescopes.

Contribution

It provides detailed predictions of nebular line fluxes and their correlation with UV magnitudes for high-redshift galaxies, guiding future observational strategies.

Findings

C IV and C III] lines are detectable in galaxies brighter than 26 AB with current telescopes.

Multiple nebular lines are promising targets for next-generation telescopes like JWST and ELTs.

High-redshift galaxies can be observed through gravitational lensing, enhancing detection prospects.

Abstract

We have performed very large and high resolution cosmological hydrodynamic simulations in order to investigate detectability of nebular lines in the rest-frame ultraviolet (UV) to optical wavelength range from galaxies at $z > 7$. We find that the expected line fluxes are very well correlated with apparent UV magnitudes. The C IV $1549 \rm \AA$ and the C III] $1909 \rm \AA$ lines of galaxies brighter than $26~ \rm AB$ are detectable with current facilities such as the VLT/XShooter and the Keck/MOSFIRE. Metal lines such as C IV $1549 \rm \AA$, C III] $1909 \rm \AA$, [O II] $3727 \rm \AA$ and [O III] $4959/5007 \rm \AA$ can be good targets for the spectroscopic observation with Thirty Meter Telescope (TMT), European Extremely Large Telescope (E-ELT), Giant Magellan Telescope (GMT) and James Webb Space Telescope (JWST). H$\alpha$ and H$\beta$ lines are also expected to be detectable with these telescopes. We also predict detectability of the nebular lines for $z > 10$ galaxies that will be found with JWST, Wide-Field Infrared Survey Telescope (WFIRST) and First Light And Reionization Explorer (FLARE) $(11 \leq z \leq 15$). We conclude that the C IV $1549 \rm \AA$, C III] $1909 \rm \AA$, [O III] $4959/5007 \rm \AA$ and H$\beta$ lines even from $z \sim 15$ galaxies can be strong targets for TMT, ELT and JWST. We also find that the magnification by gravitational lensing is of great help to detect such high-$z$ galaxies. According to our model, the C III] $1909 \rm \AA$ line in $z > 9$ galaxy candidates is detectable even using the current facilities.