Related papers: Interpreting high [O III]/Hbeta ratios with maturi…
We present Very Large Telescope/Xshooter spectrophotometric observations of eleven low-redshift (z<0.085) compact star-forming galaxies (`high O32 sample'). These galaxies are characterised by extremely high emission-line ratios…
We use Hubble Space Telescope near-IR grism spectroscopy to examine the H-beta line strengths of 260 star-forming galaxies in the redshift range 1.90 < z < 2.35. We show that at these epochs, the H-beta star formation rate (SFR) is a factor…
In systems undergoing starbursts the evolution of the young stellar population is expected to drive changes in the emission line properties. This evolution is usually studied theoretically, with a combination of evolutionary synthesis…
Four recent observational results have challenged our understanding of high--redshift galaxies, as they require the presence of far more ultraviolet photons than should be emitted by normal stellar populations. First, there is significant…
As the James Webb Space Telescope approaches scientific operation, there is much interest in exploring the redshift range beyond that accessible with Hubble Space Telescope imaging. Currently, the only means to gauge the presence of such…
We utilize medium-resolution JWST/NIRSpec observations of 164 galaxies at $z=2.0-9.3$ from the Cosmic Evolution Early Release Science (CEERS) survey to investigate the evolution of the excitation and ionization properties of galaxies at…
Strong nebular emission lines are a sensitive probe of star formation and extinction in galaxies, and the [O II] line detects star forming populations out to z>1. However, star formation rates from emission lines depend on calibration of…
We present $[OIII]/H_{\rm \beta}$ emision line flux ratio predictions for galaxies at $z \sim 7-9$ using the MAPPINGS V v5.2.0 photoionization modelling code combined with an analytic galaxy formation model. Properties such as pressure and…
We have used extensive libraries of model and empirical galaxy spectra (assembled respectively from the population synthesis code of Bruzual and Charlot and the fourth data release of the Sloan Digital Sky Survey) to interpret some puzzling…
We present Keck/MOSFIRE spectra of the diagnostic nebular emission lines [OIII]5007,4959, [OII]3727, and H-beta for a sample of 15 redshift z=3.1-3.7 Ly-alpha emitters (LAEs) and Lyman break galaxies (LBGs). In conjunction with spectra from…
We present new ISO-SWS data for a sample of 27 starburst galaxies, and with these data examine the issues of formation and evolution of the most massive stars in starburst galaxies. Using starburst models which incorporate time evolution,…
Motivated by recent observations of galaxies dominated by emission lines, which show evidence of being metal poor with young stellar populations, we present calculations of multiple model grids with a range of abundances, ionization…
We present constraints on the massive star and ionized gas properties for a sample of 62 star-forming galaxies at $z\sim2.3$. Using BPASS stellar population models, we fit the rest-UV spectra of galaxies in our sample to estimate age and…
We study and compare different examples of stellar evolutionary synthesis input parameters used to produce photoionisation model grids using the MAPPINGS V modelling code. The aim of this study is to (a) explore the systematic effects of…
Observations of high-redshift galaxies ($z >$ 5) have shown that these galaxies have extreme emission lines with equivalent widths much larger than their local star-forming counterparts. Extreme emission line galaxies (EELGs) in the nearby…
We present photoionization modeling of galaxy populations at $z\sim0$, $2$, and $> 6$ to bridge optical and far-infrared (FIR) emission-line diagrams. We collect galaxies with measurements of optical and/or FIR ([O III] 88 $\mathrm{\mu m}$…
We explore the production and escape of ionizing photons in young galaxies by investigating the ultraviolet and optical emission-line properties of models of ionization-bounded and density-bounded HII regions, active-galactic-nucleus (AGN)…
We present a study of the [OIII]5007/[OII]3727 (O32) ratios of star-forming galaxies drawn from MUSE data spanning a redshift range 0.28<z<0.85. Recently discovered Lyman continuum (LyC) emitters have extremely high oxygen line ratios:…
Lyman break galaxies (LBGs) at $z \sim 3$ exhibit number densities and clustering similar to local $L_*$ galaxies; however, their star formation rates (SFRs) are much higher. We explore the scenario in which LBGs are starburst galaxies…
We present Large Binocular Telescope spectrophotometric observations of five low-redshift (z<0.070) compact star-forming galaxies (CSFGs) with extremely high emission-line ratios O32 = [OIII]5007/[OII]3727, ranging from 23 to 43. Galaxies…