Modelling emission lines in star-forming galaxies

Baugh, CM; Lacey, Cedric G; Gonzalez-Perez, Violeta; Manzoni, Giorgio

doi:10.1093/mnras/stab3506

Modelling emission lines in star-forming galaxies Thumbnail

Authors

Professor Carlton Baugh c.m.baugh@durham.ac.uk
Professor

Professor Cedric Lacey cedric.lacey@durham.ac.uk
Professor

Violeta Gonzalez-Perez

Giorgio Manzoni

Abstract

We present a new model to compute the luminosity of emission lines in star-forming galaxies and apply this in the semi-analytical galaxy formation code GALFORM. The model combines a pre-computed grid of H II region models with an empirical determination of how the properties of H II regions depend on the macroscopic properties of galaxies based on observations of local galaxies. The new model gives a very good reproduction of the locus of star-forming galaxies on standard line ratio diagnostic diagrams. The new model shows evolution in the locus of star-forming galaxies with redshift on this line ratio diagram, with a good match to the observed line ratios at z = 1.6. The model galaxies at high redshift have gas densities and ionisation parameters that are predicted to be ≈2–3 times higher than in local star-forming galaxies, which is partly driven by the changing selection with redshift to mimic the observational selection. Our results suggest that the observed evolution in emission line ratios requires other H II region properties to evolve with redshift, such as the gas density, and cannot be reproduced by H II model grids that only allow the gas metallicity and ionisation parameter to vary.

Citation

Baugh, C., Lacey, C. G., Gonzalez-Perez, V., & Manzoni, G. (2022). Modelling emission lines in star-forming galaxies. Monthly Notices of the Royal Astronomical Society, 510(2), 1880-1893. https://doi.org/10.1093/mnras/stab3506

Journal Article Type	Article
Acceptance Date	Nov 25, 2021
Online Publication Date	Dec 3, 2021
Publication Date	2022-02
Deposit Date	Feb 10, 2022
Publicly Available Date	Feb 10, 2022
Journal	Monthly Notices of the Royal Astronomical Society
Print ISSN	0035-8711
Electronic ISSN	1365-2966
Publisher	Royal Astronomical Society
Peer Reviewed	Peer Reviewed
Volume	510
Issue	2
Pages	1880-1893
DOI	https://doi.org/10.1093/mnras/stab3506

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Copyright Statement
© The Author(s) 2021. Published by Oxford University Press on behalf of Royal Astronomical Society.<br /> This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.