Modeling the pan-spectral energy distribution of starburst galaxies. III. Emission line diagnostics of ensembles of evolving H II regions

Michael A. Dopita*, Jörg Fischera, Ralph S. Sutherland, Lisa J. Kewley, Claus Leitherer, Richard J. Tuffs, Cristina C. Popescu, Wil Van Breugel, Brent A. Groves

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    161 Citations (Scopus)

    Abstract

    We build, as far as theory will permit, self-consistent model H II regions around central clusters of aging stars. These produce strong emission line diagnostics applicable to either individual H II regions in galaxies or to the integrated emission line spectra of disk or starburst galaxies. The models assume that the expansion and internal pressure of individual H II regions is driven by the net input of mechanical energy from the central cluster, be it through winds or supernova events. This eliminates the ionization parameter as a free variable, replacing it with a parameter that depends on the ratio of the cluster mass to the pressure in the surrounding interstellar medium. These models explain why H II regions with low abundances have high excitation and demonstrate that at least part of the warm ionized medium is the result of overlapping faint, old, large, and low-pressure H II regions. We present line ratios (at both optical and IR wavelengths) that provide reliable abundance diagnostics for both single H II regions or for integrated galaxy spectra, and we find a number that can be used to estimate the mean age of the cluster stars exciting individual H II regions.

    Original languageEnglish
    Pages (from-to)177-200
    Number of pages24
    JournalAstrophysical Journal, Supplement Series
    Volume167
    Issue number2
    DOIs
    Publication statusPublished - Dec 2006

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