Nebular-line emission during the Epoch of Reionization

Wilkins, Stephen M.; Lovell, Christopher C.; Fairhurst, Ciaran; Feng, Yu; Matteo, Tiziana Di; Croft, Rupert A. C.; Kuusisto, Jussi K.; Vijayan, Aswin P.; Thomas, P.

doi:10.1093/mnras/staa649

Cited by 41 publications

(47 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this work, we model only the emission from stars (including reprocessing by gas and dust) and defer the treatment of accretion on to supermassive black holes to a future work. We broadly follow the approach implemented by Wilkins et al (2016Wilkins et al ( , 2017Wilkins et al ( , 2018Wilkins et al ( , 2020 albeit with modifications to the dust modelling as described in §2.4.…”

Section: Spectral Energy Distribution Modellingmentioning

confidence: 99%

“…Throughout this work we utilise v2.2.1 of the Binary Population and Spectral Synthesis (BPASS) stellar population synthesis (SPS) models (Stanway & Eldridge 2018) and assume a Chabrier initial mass function (IMF) throughout (Chabrier 2003). As explored in Wilkins et al (2016Wilkins et al ( , 2017Wilkins et al ( , 2018Wilkins et al ( , 2020 the choice of SPS and IMF can have a large effect on resulting broadband luminosities and emission line quantities.…”

Section: Stellar Emissionmentioning

confidence: 99%

“…To account for the reprocessing of these photons by surrounding gas we associate each young (t < 10 Myr) star particle with a surrounding Hii region (or birth cloud) powered by its LyC emission. To calculate the nebular emission we follow the approach detailed in Wilkins et al (2020). In short, the pure stellar spectrum of each star particle is input to the cloudy (Ferland et al 2017) photo-ionisation code.…”

Section: Nebular Emissionmentioning

confidence: 99%

“…This results in increased dust attenuation in Flares compared to BlueTides in , and thus cause differences in the observed UV continuum, attenuation and line luminosity values presented in the next sections. However, a direct comparison to Wilkins et al (2017Wilkins et al ( , 2020, which also implemented a similar line-of-sight attenuation model, is not possible due to the difference in the modelling approach, namely the implementation of birth cloud attenuation and the dependence on an evolving DTM ratio.…”

Section: Comparison With Observations and Modelsmentioning

confidence: 99%

See 3 more Smart Citations

First Light And Reionisation Epoch Simulations (FLARES) II: The Photometric Properties of High-Redshift Galaxies

Vijayan

Lovell

Wilkins

et al. 2020

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

We present the photometric properties of galaxies in the First Light and Reionisation Epoch Simulations (Flares). The simulations trace the evolution of galaxies in a range of overdensities through the Epoch of Reionistion (EoR). With a novel weighting scheme we combine these overdensities, extending significantly the dynamic range of observed composite distribution functions compared to periodic simulation boxes. Flares predicts a significantly larger number of intrinsically bright galaxies, which can be explained through a simple model linking dust-attenuation to the metal content of the interstellar medium, using a line-of-sight (LOS) extinction model. With this model we present the photometric properties of the Flares galaxies for z ∈ [5, 10]. We show that the ultraviolet (UV) luminosity function (LF) matches the observations at all redshifts. The function is fit by Schechter and double power-law forms, with the latter being favoured at these redshifts by the Flares composite UV LF. We also present predictions for the UV continuum slope as well as the attenuation in the UV. The impact of environment on the UV LF is also explored, with the brightest galaxies forming in the densest environments. We then present the line luminosity and equivalent widths of some prominent nebular emission lines arising from the galaxies, finding rough agreement with available observations. We also look at the relative contribution of obscured and unobscured star formation, finding comparable contributions at these redshifts.

show abstract

Section: Spectral Energy Distribution Modellingmentioning

confidence: 99%

Section: Stellar Emissionmentioning

confidence: 99%

Section: Nebular Emissionmentioning

confidence: 99%

Section: Comparison With Observations and Modelsmentioning

confidence: 99%

See 2 more Smart Citations

First Light And Reionisation Epoch Simulations (FLARES) II: The Photometric Properties of High-Redshift Galaxies

Vijayan

Lovell

Wilkins

et al. 2020

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

show abstract

“…Another approach is to use high-resolution hydrodynamic simulations of galaxies, ideally including radiation transfer and a proper treatment of the ISM, to predict the resulting emission lines and compare them to observations. Such models, with fairly different degrees of sophistication have for example been presented by Shimizu et al (2016), Hirschmann et al (2017, Katz et al (2019), Wilkins et al (2020), and by Pellegrini et al (2020) for smaller scales. These simulations are able to capture several observational trends and allow useful predictions, in particular for high-redshift galaxies.…”

Section: Future Improvementsmentioning

confidence: 99%

Reconciling escape fractions and observed line emission in Lyman-continuum-leaking galaxies

Ramambason

Schaerer

Stasińska

et al. 2020

A&A

View full text Add to dashboard Cite

Context. Finding and elucidating the properties of Lyman-continuum(LyC)-emitting galaxies is an important step in improving our understanding of cosmic reionization. Aims. Although the z ∼ 0.3 − 0.4 LyC emitters found recently show strong optical emission lines, no consistent quantitative photoionization model taking into account the escape of ionizing photons and inhomogenous interstellar medium (ISM) geometry of these galaxies has yet been constructed. Furthermore, it is unclear to what extent these emission lines can be used to distinguish LyC emitters. Methods. To address these questions we construct one- and two-zone photoionization models accounting for the observed LyC escape, which we compare to the observed emission line measurements. The main diagnostics used include lines of [O III], [O II], and [O I] plus sulfur lines ([S II], [S III]) and a nitrogen line ([N II]), which probe regions of different ionization in the ISM. Results. We find that single (one-zone) density-bounded photoionization models cannot reproduce the emission lines of the LyC leakers, as pointed out by earlier studies, because they systematically underpredict the lines of species of low ionization potential, such as [O I] and [S II]. Introducing a two-zone model, with differing ionization parameter and a variable covering fraction and where one of the zones is density-bounded, we show that the observed emission line ratios of the LyC emitters are well reproduced. Furthermore, our model yields LyC escape fractions, which are in fair agreement with the observations and independent measurements. The [O I] λ6300 excess, which is observed in some LyC leakers, can be naturally explained in this model, for example by emission from low-ionization and low-filling-factor gas. LyC emitters with a high escape fraction (fesc ≳ 38%) are deficient both in [O I] λ6300 and in [S II] λλ6716,6731. We also confirm that a [S II] λλ6716,6731 deficiency can be used to select LyC emitter candidates, as suggested earlier. Finally, we find indications for a possible dichotomy in terms of escape mechanisms for LyC photons between galaxies with relatively low (fesc ≲ 10%) and higher escape fractions. Conclusions. We conclude that two-zone photoionization models are sufficient and required to explain the observed emission line properties of z ∼ 0.3 − 0.4 LyC emitters. This is in agreement with UV absorption line studies, which also show the co-existence of regions with high hydrogen column density (i.e., no escape of ionizing photons) and density-bounded or very low column density regions responsible for the observed escape of LyC radiation. These simple but consistent models provide a first step towards the use of optical emission lines and their ratios as quantitative diagnostics of LyC escape from galaxies.

show abstract

Euclid preparation

Scharré,

Hirschmann,

De Lucia

et al. 2024

A&A

View full text Add to dashboard Cite

In anticipation of the upcoming Euclid Wide and Deep Surveys, we present optical emission-line predictions at intermediate redshifts from 0.4 to 2.5. Our approach combines a mock light cone from the Gaea semi-analytic model with advanced photoionisation models to construct emission-line catalogues. This allows us to self-consistently model nebular emission from H ii regions around young stars, and, for the first time with a semi-analytic model, narrow-line regions of active galactic nuclei (AGN) and evolved stellar populations. Gaea Mpc $, marks the largest volume this set of models has been applied to. We validate our methodology against observational and theoretical data at low redshift. Our analysis focuses on seven optical emission lines: Halpha , Hbeta S ii N ii O i O iii 5007$, and O ii 3727, 3729$. In assessing selection bias, we find that it will predominantly observe line-emitting galaxies, which are massive (stellar mass $ solarmass $), star-forming (specific star-formation rate $> 10^ yr^ $), and metal-rich (oxygen-to-hydrogen abundance $ logten(O/H)+12 > 8$). We provide percentages of emission-line populations in our underlying Gaea sample with a mass resolution limit of $10^ solarmass $ and an $H$-band magnitude cut of 25. We compare results with and without an estimate of interstellar dust attenuation, which we model using a Calzetti law with a mass-dependent scaling. According to this estimate, the presence of dust may decrease observable percentages by a further 20-30<!PCT!> with respect to the overall population, which presents challenges for detecting intrinsically fainter lines. We predict to observe around 30--70<!PCT!> of Halpha - N ii S ii -, and O iii -emitting galaxies at redshift below 1. At higher redshift, these percentages decrease below 10<!PCT!>. Hbeta O ii and O i emission are expected to appear relatively faint, thus limiting observability to at most 5<!PCT!> at the lower end of their detectable redshift range, and below 1<!PCT!> at the higher end. This is the case both for these lines individually and in combination with other lines. For galaxies with line emission above the flux threshold in the Euclid Deep Survey, we find that BPT diagrams can effectively distinguish between different galaxy types up to around redshift 1.8, attributed to the bias toward metal-rich systems. Moreover, we show that the relationships of Halpha and O iii +Hbeta to the star-formation rate, as well as the O iii -AGN luminosity relation, exhibit minimal, if any, changes with increasing redshift when compared to local calibrations. Based on the line ratios $ N ii /H N ii O ii $, and $ N ii S ii $, we further propose novel redshift-invariant tracers for the black hole accretion rate-to-star formation rate ratio. Lastly, we find that commonly used metallicity estimators display gradual shifts in normalisations with increasing redshift, while maintaining the overall shape of local calibrations. This is in tentative agreement with recent JWST data.

show abstract

Nebular-line emission during the Epoch of Reionization

Cited by 41 publications

References 45 publications

First Light And Reionisation Epoch Simulations (FLARES) II: The Photometric Properties of High-Redshift Galaxies

First Light And Reionisation Epoch Simulations (FLARES) II: The Photometric Properties of High-Redshift Galaxies

Reconciling escape fractions and observed line emission in Lyman-continuum-leaking galaxies

Euclid preparation

Contact Info

Product

Resources

About