A geostatistical analysis of multiscale metallicity variations in galaxies [II]: Predicting the metallicities of Hii and diffuse ionised gas regions via universal kriging

Abstract

The metallicity of diffuse ionised gas (DIG) cannot be determined using strong emission line diagnostics, which are calibrated to calculate the metallicity of Hii regions. Because of this, resolved metallicity maps from integral field spectroscopy (IFS) data remain largely incomplete. In this paper (the second of a series), we introduce the geostatistical technique of universal kriging, which allows the complete 2D metallicity distribution of a galaxy to be reconstructed from metallicities measured at Hii regions, accounting for spatial correlations between nearby data points. We apply this method to construct high-fidelity metallicity maps of the local spiral galaxy NGC 5236 using data from the TYPHOON/PrISM survey. We find significant correlation in the metallicity of Hii regions separated by up to 0.4-1.2 kpc. Predictions constructed using this method were tested using cross-validation in Hii regions, and we show that they outperform significantly interpolation based on metallicity gradients. Furthermore, we apply kriging to predict the metallicities in regions dominated by DIG emission, considering seven additional spiral galaxies with high resolution (<100pc) metallicity maps. We compare kriging maps to DIG metallicities computed with novel ionisation corrections, and find that such corrections introduce a systematic offset of up to $\pm 0.1$ dex for any individual galaxy, with a scatter of 0.02-0.07 dex for the sample. Overall we recommend universal kriging, together with a calibrated geostatistical model, as the superior method for inferring the metallicities of DIG-dominated regions in local spiral galaxies, demonstrating further the potential of applying geostatistical methods to spatially resolved galaxy observations.

26 pages, 11 figures, including 2 appendices. Accepted for publication in MNRAS

References in corpus (31)

• Overview of the SDSS-IV MaNGA Survey: Mapping Nearby Galaxies at Apache Point Observatory
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• Understanding Galaxy Evolution through Emission Lines
• The SAMI Galaxy Survey: instrument specification and target selection
• An Objective Definition for the Main Sequence of Star-Forming Galaxies
• The Mass-Metallicity and the Fundamental Metallicity Relation revisited on a fully Te-based abundance scale for galaxies
• New fully empirical calibrations of strong-line metallicity indicators in star forming galaxies
• A z=0 Multi-wavelength Galaxy Synthesis I: A WISE and GALEX Atlas of Local Galaxies
• The PHANGS-MUSE survey -- Probing the chemo-dynamical evolution of disc galaxies
• SDSS-IV MaNGA: The Impact of Diffuse Ionized Gas on Emission-line Ratios, Interpretation of Diagnostic Diagrams, and Gas Metallicity Measurements
• Star formation sustained by gas accretion
• Diffuse ionized gas in galaxies across the Hubble sequence at the CALIFA resolution
• IZI: Inferring the Gas Phase Metallicity (Z) and Ionization Parameter (q) of Ionized Nebulae using Bayesian Statistics
• First results from SMAUG: Characterization of Multiphase Galactic Outflows from a Suite of Local Star-Forming Galactic Disk Simulations
• The MUSE Atlas of Disks (MAD): Resolving Star Formation Rates and Gas Metallicities on < 100pc Scales
• LZIFU: an emission-line fitting toolkit for integral field spectroscopy data
• Young stars and ionized nebulae in M83: comparing chemical abundances at high metallicity
• The KLEVER Survey: Spatially resolved metallicity maps and gradients in a sample of 1.2 < z < 2.5 lensed galaxies
• The Chemical Evolution Carousel of Spiral Galaxies: Azimuthal Variations of Oxygen Abundance in NGC1365
• Starburst-AGN mixing: II. Optically-selected active galaxies
• The Effects of Diffuse Ionized Gas and Spatial Resolution on Metallicity Gradients: TYPHOON Two-Dimensional Spectrophotometry of M83
• Metallicity calibrations for diffuse ionised gas and low ionisation emission regions
• Large Metallicity Variations in the Galactic Interstellar Medium
• The role of galactic dynamics in shaping the physical properties of giant molecular clouds in Milky Way-like galaxies
• The Two-Dimensional Metallicity Distribution and Mixing Scales of Nearby Galaxies
• Metallicity, ionization parameter, and pressure variations of HII regions in the TYPHOON spiral galaxies
• Three-dimensional extinction mapping using Gaussian random fields
• The diffuse ionized gas (DIG) in star-forming galaxies: the influence of aperture effects on local HII regions
• A geostatistical analysis of multiscale metallicity variations in galaxies [I]: Introduction and comparison of high-resolution metallicity maps to an analytic metal transport model
• Disks as Inhomogeneous, Anisotropic Gaussian Random Fields
• Detection of Extraplanar Diffuse Ionized Gas in M83

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