The impact of the nitrogen-to-oxygen ratio on ionized nebula diagnostics based on [N ii] emission lines

By E. P'erez-Montero, Thierry Contini. 2009

211 citations recorded by the source corpus.

We study the relation between nitrogen and oxygen abundances as a function of metallicity for a sample of emission-line objects for which a direct measurement of the metallicity has been possible. This sample is representative of the very different conditions in ionization and chemical enrichment that we can find in the Universe. We first construct the N/O versus O/H ratio diagram, and discuss its large dispersion at all metallicity regimes. Using the same sample and a large grid of photoionization models covering very different values of the N/O ratio, we then study the most widely used strong-line calibrators of metallicity based on [N II] emission lines, such as N2 and 03N2. We demonstrate that these parameters underestimate the metallicity at low N/O ratios and vice versa. We also investigate the effect of the N/O ratio on different diagnostic diagrams used to discriminate narrow-line active galactic nuclei from star-forming regions, such as the [O III ]/Hβ versus [N II ]/Hα, and show that a large fraction of the galaxies catalogued as composite in this diagram can be, in fact, star-forming galaxies with a high value of the N/O ratio. Finally, using strong-line methods sensitive to the N/O abundance ratio, like N202 and N2S2, we investigate the relation between this ratio and the stellar mass for the galaxies of the Sloan Digital Sky Survey. We find, as in the case of the mass-metallicity relation, a correlation between these two quantities and a flattening of the relation for the most massive galaxies, which could be a consequence of the enhancement of the dispersion of N/O ratio in the high-metallicity regime.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/5006389785fb3cf508f4ae63bf38b4a4cecab507

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Citations in the corpus

THE MASS–METALLICITY RELATION WITH THE DIRECT METHOD ON STACKED SPECTRA OF SDSS GALAXIES (2012, methodology): “M relation has been previously investigated by Pérez-Montero & Contini (2009) and Pérez-Montero et al. (2013), who used strong line methods to estimate N/O.”
THE MOSDEF SURVEY: ELECTRON DENSITY AND IONIZATION PARAMETER AT z ∼ 2.3 (2015, methodology): “…local universe, the N/O abundance ratio is observed to have a dependence on O/H, such that N/O is a constant value at low abundance but begins to rise roughly linearly with O/H at higher abundance (Pérez-Montero & Contini 2009; Pilyugin et al. 2012; Andrews & Martini 2013; Pérez-Montero 2014).”
Nebular Emission Line Ratios in z ≃ 2–3 Star-forming Galaxies with KBSS-MOSFIRE: Exploring the Impact of Ionization, Excitation, and Nitrogen-to-Oxygen Ratio (2016, methodology): “At z ∼ 0, many studies rely on measurements from the spectra of individual compact galaxies or local H II regions (e.g., Pérez-Montero & Contini 2009; Pilyugin et al. 2012) or from composite spectra of relatively metal-poor galaxies (Andrews & Martini 2013), but the typical value of N/O at a given…”
SDSS-IV MaNGA : the impact of diffuse ionized gas on emission-line ratios, interpretation of diagnostic diagrams and gas metallicity measurements (2016, methodology): “This calibration fails for any systems deviating from the assumed N/O−O/H relation.”
PHYSICAL PROPERTIES OF EMISSION-LINE GALAXIES AT z ∼ 2 FROM NEAR-INFRARED SPECTROSCOPY WITH MAGELLAN FIRE (2014, background): “One possible cause of such an offset is a higher average nitrogen-to-oxygen abundance ratio (Pérez-Montero & Contini 2009).”
THE MOSDEF SURVEY: EXCITATION PROPERTIES OF z ∼ 2.3 STAR-FORMING GALAXIES (2014, methodology): “N2O2 has been calibrated by Pérez-Montero & Contini (2009) for local galaxies as a proxy for the N/O abundance ratio (log(N/O) = 0.93 × N2O2 − 0.20).”
Eliminating error in the chemical abundance scale for extragalactic H ii regions (2012, background): “Yin et al (2007) indicated that the N2 and the O3N2 indices are only useful for calibrating metallicities of galaxies with 12+log(O/H) 8.5, while Pérez-Montero & Contini (2009) established that empirical calibrations using the O3N2 parameter are not valid for objects with 12+log(O/H).8.0.”
The SINS/zC-SINF Survey of z ∼ 2 Galaxy Kinematics: SINFONI Adaptive Optics–assisted Data and Kiloparsec-scale Emission-line Properties (2018, methodology): “…and possible N/O abundance variations on the [N II]/Hα ratio, as amply discussed in the literature 5 (e.g., Kewley & Dopita 2002; Kewley et al. 2013; Pérez-Montero & Contini 2009; Yuan et al. 2012; Andrews & Martini 2013; Steidel et al. 2014; Shapley et al. 2015; Sanders et al. 2015, 2017;…”
Deriving model-based Te-consistent chemical abundances in ionized gaseous nebulae (2014, methodology): “According to Pérez-Montero & Contini (2009), some emission-line ratios between [N ii] and other low-excitation emission-line, such as [O ii] (N2O2) or [S ii] (N2S2) depend basically on N/O.”
STRONG NEBULAR LINE RATIOS IN THE SPECTRA of z ∼ 2–3 STAR FORMING GALAXIES: FIRST RESULTS FROM KBSS-MOSFIRE (2014, methodology): “The issue of how N/O affects strong line methods of measuring O/H is discussed in detail by Pérez-Montero & Contini (2009); see section 4.5.”
DIRECT OXYGEN ABUNDANCES FOR LOW-LUMINOSITY LVL GALAXIES (2012, methodology): “Empirical and theoretical oxygen abundance calibrations often introduce bias, further limiting the M-Z relationship (e.g., Yin et al. 2007; Pérez-Montero & Contini 2009; Moustakas et al. 2010; Berg et al. 2011).”
Integral field spectroscopy with SINFONI of VVDS galaxies I. Galaxy dynamics and mass assembly at 1.2 < z < 1.6 (2009, methodology): “Using the last calibrations proposed by Pérez-Montero & Contini (2009), we have estimated Fig.”