Modelling the Pan-Spectral Energy Distribution of Starburst Galaxies: II. Control of the \HII Region Parameters

Abstract

We examine, from a theoretical viewpoint, how the physical parameters of HII regions are controlled in both normal galaxies and in starburst environments. These parameters are the HII region luminosity function, the time-dependent size, the covering fraction of molecular clouds, the pressure in the ionized gas and the ionization parameter. The factors which control them are the initial mass function of the exciting stars, the cluster mass function, the metallicity and the mean pressure in the surrounding interstellar medium. We investigate the sensitivity of the H$\alpha$ luminosity to the IMF, and find that this can translate to more than a factor two variation in derived star formation rates. The molecular cloud dissipation timescale is estimated from a case study of M17 to be $\sim 1$ Myr for this object. Based upon HII luminosity function fitting for nearby galaxies, we suggest that the \HII region cluster mass function is fitted by a log-normal form peaking at $\sim 100M_{\odot }$. The cluster mass function continues the stellar IMF to higher mass. The pressure in the HII regions is controlled by the mechanical luminosity flux from the central cluster. Since this is closely related to the ionizing photon flux, we show that the ionization parameter is not a free variable, and that the diffuse ionized medium may be composed of many large, faint and old HII regions. Finally, we derive theoretical probability distributions for the ionization parameter as a function of metallicity and compare these to those derived for SDSS galaxies.

36 pages, 8 figures. To be published in Astrophysical Journal, August 2006

Cited by in corpus (53)

• Understanding Galaxy Evolution through Emission Lines
• Extragalactic chemical abundances: do HII regions and young stars tell the same story? The case of the spiral galaxy NGC 300
• Modelling the Pan-Spectral Energy Distribution of Starburst Galaxies: IV The Controlling Parameters of the Starburst SED
• Stellar Evolutionary Effects on the Abundances of PAH and SN-Condensed Dust in Galaxies
• The oxygen abundance in the inner HII regions of M101. Implications for the calibration of strong-line metallicity indicators
• Synthetic Galaxy Images and Spectra from the Illustris Simulation
• Should we believe the results of UV-mm galaxy SED modelling?
• Imprints of galaxy evolution on H ii regions Memory of the past uncovered by the CALIFA survey
• Using H-alpha Morphology and Surface Brightness Fluctuations to Age-Date Star Clusters in M83
• Numerical Simulations of Turbulent, Molecular Clouds Regulated by Radiation Feedback Forces I: Star Formation Rate and Efficiency
• Galaxies in the Illustris simulation as seen by the Sloan Digital Sky Survey - II: Size-luminosity relations and the deficit of bulge-dominated galaxies in Illustris at low mass
• The COSMOS [OII] Survey: Evolution of Electron Density with Star Formation Rate
• JADES: Detecting [OIII]$\lambda 4363$ Emitters and Testing Strong Line Calibrations in the High-$z$ Universe with Ultra-deep JWST/NIRSpec Spectroscopy up to $z\sim 9.5$
• CLASSY IV: Exploring UV diagnostics of the interstellar medium in local high-$z$ analogs at the dawn of the JWST era
• The X-SHOOTER Lyman-$\alpha$ survey at z=2 (XLS-z2) I: What makes a galaxy a Lyman-$\alpha$ emitter?
• Massive Compact Galaxies with High-Velocity Outflows: Morphological Analysis and Constraints on AGN Activity
• A JWST/NIRSpec Exploration of the Connection between Ionization Parameter, Electron Density, and Star-Formation-Rate Surface Density in z=2.7-6.3 Galaxies
• PHANGS-JWST First Results: Destruction of the PAH molecules in HII regions probed by JWST and MUSE
• Pégase.3: A code for modeling the UV-to-IR/submm spectral and chemical evolution of galaxies with dust
• SDSS 0809+1729: Connections Between Extremely Metal Poor Galaxies and Gamma Ray Burst Hosts
• Ionization correction factors and dust depletion patterns in giant HII regions
• Comparing the pre-SNe feedback and environmental pressures for 6000 HII regions across 19 nearby spiral galaxies
• Mid-infrared diagnostics of starburst galaxies: clumpy, dense structures in star-forming regions in the Antennae (NGC 4038/4039)
• Spectroscopic Confirmation of an Ultra Massive and Compact Galaxy at z=3.35: A Detailed Look at an Early Progenitor of Local Most Massive Ellipticals
• On the far-infrared metallicity diagnostics: applications to high-redshift galaxies
• Metallicity, ionization parameter, and pressure variations of HII regions in the TYPHOON spiral galaxies
• Enhanced Star Formation of Less Massive Galaxies in a Proto-Cluster at z=2.5
• H$\alpha$ Morphologies of Star Clusters in 16 LEGUS Galaxies: Constraints on HII region evolution timescales
• Deep Fabry-Perot Halpha Observations of NGC 7793: a Very Extended Halpha Disk and a Truly Declining Rotation Curve
• Inferring gas-phase metallicity gradients of galaxies at the seeing limit: A forward modelling approach
• Numerical Simulations of Turbulent Molecular Clouds Regulated by Radiation Feedback Forces II: Radiation-Gas Interactions and Outflows
• HST Emission Line Galaxies at z ~ 2: The Mystery of Neon
• The Impact of Star-Formation-Rate Surface Density on the Electron Density and Ionization Parameter of High-Redshift Galaxies
• Disentangling the physical parameters of gaseous nebulae and galaxies
• On the impact of radiation pressure on the dynamics and inner structure of dusty wind-driven shells
• Correlation between the gas-phase metallicity and ionization parameter in extragalactic HII regions
• A multiwavelength study of the Magellanic-type galaxy NGC 4449 - I. Modelling the spectral energy distribution, the ionization structure and the star formation history
• Stellar associations powering HII regions $\unicode{x2013}$ I. Defining an evolutionary sequence
• LIMFAST. I. A Semi-Numerical Tool for Line Intensity Mapping
• Gaps in the cloud cover? Comparing extinction measures in spiral disks
• The Opacity of Spiral Galaxy Disks VIII: Structure of the Cold ISM
• Metal-poor dwarf galaxies in the SIGRID galaxy sample. II. The electron temperature-abundance calibration and the parameters that affect it
• Optical and infrared emission of H II complexes as a clue to the PAH life cycle
• TODDLERS: A new UV-mm emission library for star-forming regions. 1. Integration with SKIRT and public release
• The resolved chemical abundance properties within the interstellar medium of star-forming galaxies at $\text{z}\approx 1.5$
• New Ionization Models and the Shocking Nitrogen Excess at z > 5
• Rest-frame UV and optical emission line diagnostics of ionised gas properties: a test case in a star-forming knot of a lensed galaxy at z~1.7
• Astrophysics in 2006
• On emission-line spectra obtained from evolutionary synthesis models II. Scale-relations and the estimation of mass dependences
• Polycyclic aromatic hydrocarbons destruction in star-forming regions across 42 nearby galaxies
• Constraints on Galaxy Structure and Evolution from the Light of Nearby Systems
• Recovering the properties of the interstellar medium through integrated spectroscopy: application to the z~0 ECO volume-limited star-forming galaxy sample
• Massive stars in the nuclei and arms of spirals