Nebular Continuum and Line Emission in Stellar Population Synthesis Models

By N. Byler, J. J. Dalcanton, C. Conroy, Benjamin D. Johnson. 2016

281 citations recorded by the source corpus.

Accounting for nebular emission when modeling galaxy spectral energy distributions (SEDs) is important, as both line and continuum emissions can contribute significantly to the total observed flux. In this work, we present a new nebular emission model integrated within the Flexible Stellar Population Synthesis code that computes the line and continuum emission for complex stellar populations using the photoionization code Cloudy. The self-consistent coupling of the nebular emission to the matched ionizing spectrum produces emission line intensities that correctly scale with the stellar population as a function of age and metallicity. This more complete model of galaxy SEDs will improve estimates of global gas properties derived with diagnostic diagrams, star formation rates based on Hα, and physical properties derived from broadband photometry. Our models agree well with results from other photoionization models and are able to reproduce observed emission from H ii regions and star-forming galaxies. Our models show improved agreement with the observed H ii regions in the Ne iii/O ii plane and show satisfactory agreement with He ii emission from z = 2 galaxies, when including rotating stellar models. Models including post-asymptotic giant branch stars are able to reproduce line ratios consistent with low-ionization emission regions. The models are integrated into current versions of FSPS and include self-consistent nebular emission predictions for MIST and Padova+Geneva evolutionary tracks.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/7691c80db715ea6169551da4549fe3989eed4eb2

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In Astronomy and Astrophysics

1. L. Hernquist
2. Volker Springel
3. P. Hopkins
4. M. Vogelsberger
5. Shy Genel
6. C. Conroy
7. P. Torrey
8. R. Dav'e

In Instrumentation

1. L. Hernquist
2. Volker Springel
3. P. Hopkins
4. C. Conroy
5. M. Vogelsberger
6. Shy Genel
7. R. Dav'e
8. P. Torrey

Citations in the corpus

• Binary Population and Spectral Synthesis Version 2.1: Construction, Observational Verification, and New Results (2017, methodology): “This measures the ratio of the number of ionising photons to the local gas density, and is thus constructed through the combination of appropriate stellar atmosphere models and a choice of gas distribution (e.g. Byler et al. 2017).”
• UniverseMachine: The correlation between galaxy growth and dark matter halo assembly from z = 0−10 (2018, methodology): “0 (Conroy et al. 2009; Conroy & Gunn 2010; Byler et al. 2017) to tabulate the simple stellar population (SSP) luminosity per unit stellar mass as a function of age, metallicity, and dust (L(t,Z,D)), assuming a Chabrier (2003) IMF and the Calzetti et al. (2000) dust model.”
• Inferring the star formation histories of massive quiescent galaxies with bagpipes: evidence for multiple quenching mechanisms (2017, methodology): “The nebular-emission model implemented in Bagpipes is constructed following themethodology of Byler et al. (2017), using the latest (2017) version of the Cloudy photoionization code (Ferland et al. 2017).”
• First results from the TNG50 simulation: galactic outflows driven by supernovae and black hole feedback (2019, background): “…a level of modeling detail which would also enable direct predictions of synthetic nebular emission lines from the ISM itself (Gutkin et al. 2016; Byler et al. 2017), as well as extended and extraplanar ionized gas reservoirs (e.g. Jones et al. 2017), in the context of cosmological galaxy…”
• JWST Census for the Mass–Metallicity Star Formation Relations at z = 4–10 with Self-consistent Flux Calibration and Proper Metallicity Calibrators (2023, methodology): “We use the stellar population synthesis package, Flexible Stellar Population Synthesis ( FSPS; Conroy et al. 2009; Conroy & Gunn 2010 ) for the stellar SEDs, and include nebular emission from the photoionization models of Cloudy ( Byler et al. 2017 ) .”
• A JWST/NIRSpec First Census of Broad-line AGNs at z = 4–7: Detection of 10 Faint AGNs with M BH ∼ 106–108 M ⊙ and Their Host Galaxy Properties (2023, methodology): “We use the stellar population synthesis package, Flexible Stellar Population Synthesis (FSPS; Conroy et al. 2009; Conroy & Gunn 2010) for stellar SEDs, and include nebular emission from the photoionization models of Cloudy (Byler et al. 2017).”
• Stellar Population Inference with Prospector (2020, methodology): “As described in §A the emission line model included with FSPS is based on Cloudy (Ferland et al. 2013; Byler et al. 2017).”
• The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VII. Properties of the Host Galaxy and Constraints on the Merger Timescale (2017, background): “Nebular line and continuum emission are added self-consistently through use of CLOUDY model grids from Byler et al. (2017).”