Biases in abundance derivations for metal-rich nebulae

By G. Stasińska. 2005

137 citations recorded by the source corpus.

Using ab-initio photoionization models of giant H ii regions, we test methods for abundance determinations based on a direct measurement of the electron temperature, now possible even for moderate to high-metallicity objects. We find that, for metallicities larger than solar, the computed abundances deviate systematically from the real ones, generally by larger amounts for more metal-rich H ii regions. We discuss the reasons for this, and present diagrams allowing the reader to better understand the various factors coming into play. We briefly discuss less classical methods to derive abundances in metal-rich H ii regions. In particular, we comment on the interest of the oxygen and carbon recombination lines. We also show that, contrary to the case of giant H ii regions, the physical conditions in bright extragalactic planetary nebulae are such that their chemical composition can be accurately derived even at high metallicities. Thus, extragalactic planetary nebulae are promising potential probes of the metallicity of the interstellar medium in the internal parts of spiral galaxies as well as in metal-rich elliptical galaxies.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/b3d98f474a395b9bdb184fa2839c92bd120f4917

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Citations in the corpus

New fully empirical calibrations of strong-line metallicity indicators in star forming galaxies (2016, methodology): “…and the age of the ionizing source (Moustakas et al. 2010) and on the other hand to temperature gradients and fluctuations that may cause an overestimate of the electron temperature and a consequent underestimate of the true metallicity with the Te method (Peimbert 1967; Stasińska 2002, 2005).”
Modelling the nebular emission from primeval to present-day star-forming galaxies (2016, background): “…models must also be invoked to compute the gas-phase abundances of other heavy elements (e.g., C, N, S), which requires estimates of the electron temperatures pertaining to the zones populated by the corresponding ions (e.g., Garnett 1992; Izotov & Thuan 1999; Stasińska 2005; Izotov et al. 2006).”
The mass–metallicity and the fundamental metallicity relation revisited on a fully Te-based abundance scale for galaxies (2019, background): “…by a certain number of weaknesses, mainly attributed to the presence of temperature and chemical inhomogeneities in the nebulae (Peimbert 1967; Stasińska 2002, 2005) and/or to the contribution of diffuse gas to line emission when dealing with global galaxy spectra (Sanders et al. 2017; Zhang…”
The chemical composition of metal-poor emission-line galaxies in the Data Release 3 of the Sloan Digital Sky Survey (2005, methodology): “Following Stasińska (2005) we do not attempt to analyze the collisional strengths for Fe2+ and use the same ones as in Thuan et al. (1995).”
THE MASS–METALLICITY RELATION WITH THE DIRECT METHOD ON STACKED SPECTRA OF SDSS GALAXIES (2012, background): “Such an effect would cause the direct method metallicities to be biased low (Stasińska 2005; Bresolin 2008).”
The Mass-Metallicity Relation at z≳2 (2006, background): “The Te method itself is not without difficulties, however, as temperature gradients or fluctuations in the H II regions may affect abundance determinations at high metallicities (Stasińska 2005).”
OPTICAL SPECTROSCOPY AND NEBULAR OXYGEN ABUNDANCES OF THE SPITZER/SINGS GALAXIES (2010, background): “Peimbert (1967) was the first to point out that temperature inhomogeneities in H ii regions could cause the electron temperature inferred from the collisionally excited forbidden lines to be overestimated, and therefore the abundance to be underestimated (Stasińska 2005; Bresolin 2006).”
Metallicity Calibrations and the Mass-Metallicity Relation for Star-forming Galaxies (2008, methodology): “The theoretical investigation by (Stasińska 2005) predicts that these lines can provide robust metallicities up to ∼ solar (12 + log(O/H)= 8.7; Allende Prieto et al. 2001), but they may underestimate the abundance at metallicities above solar if temperature fluctuations or gradients exist in the…”
Metallicity and Nuclear Star Formation in Nearby Galaxy Pairs: Evidence for Tidally Induced Gas Flows (2005, background): “The cause of this offset is un- known (see Garnett et al. 2004b,a; Stasińska 2005, for a discussion).”
A VLT study of metal-rich extragalactic H II regions - I. Observations and empirical abundances (2005, background): “At high metallicity, however, the auroral lines do not necessarily provide a good measure of Te, due to the biases introduced by the presence of temperature gradients within the nebulae (Stasińska 2005).”
STRONG NEBULAR LINE RATIOS IN THE SPECTRA of z ∼ 2–3 STAR FORMING GALAXIES: FIRST RESULTS FROM KBSS-MOSFIRE (2014, background): “It has also been argued that Te-based metallicities may be biased low due to temperature gradients and/or by the details of the electron energy distribution (e.g., Stasińska 2005; Dopita et al. 2013).”
EXTRAGALACTIC CHEMICAL ABUNDANCES: DO H ii REGIONS AND YOUNG STARS TELL THE SAME STORY? THE CASE OF THE SPIRAL GALAXY NGC 300 (2009, background): “Although this approach is potentially prone to systematic errors due to the effects of temperature gradients within the nebulae at high abundance (Stasińska 2005), the data suggest that the direct abundances are reliable at least up to the solar value (Bresolin 2007).”
The relation between metallicity, stellar mass and star formation in galaxies: an analysis of observational and model data (2011, background): “…2006), saturation at high metallicities (Kewley & Dopita 2002; Erb et al. 2006; Liang et al. 2006; Kewley & Ellison 2008) and inconsistency with Te derived metallicities (Kennicutt, Bresolin & Garnett 2003; Bresolin, Garnett & Kennicutt 2004; Garnett, Kennicutt & Bresolin 2004; Stasińska 2005).”
Semi‐empirical analysis of Sloan Digital Sky Survey galaxies – III. How to distinguish AGN hosts (2006, methodology): “For more metal-rich objects, the abundances are generally derived from empirical methods (which are of statistical value), although in a few cases abundances can now be derived by direct methods also (which, in this case, should be examined for possible biases as shown by Stasińska 2005).”
Eliminating error in the chemical abundance scale for extragalactic H ii regions (2012, methodology): “This is in agreement with the work of Stasińska (2002) and Stasińska (2005), who predicted that temperature gradients in these high-metallicity H ii regions can cause the abundances to be underestimated by as much as ∼ 0.4 dex.”
KECK HIRES SPECTROSCOPY OF EXTRAGALACTIC H ii REGIONS: C AND O ABUNDANCES FROM RECOMBINATION LINES (2009, background): “As it has been demonstrated by Stasińska (1978, 2005), high-metallicity—and lowtemperature—”