Effects of a {kappa}-distribution in HII regions

DOI

Recently, Nicholls et al. (2012ApJ...752..148N), inspired by in situ observations of solar system astrophysical plasmas, suggested that the electrons in H II regions are characterized by a {kappa}-distribution of energies rather than a simple Maxwell-Boltzmann distribution. Here, we have collected together new atomic data within a modified photoionization code to explore the effects of both the new atomic data and the {kappa}-distribution on the strong-line techniques used to determine chemical abundances in H II regions. By comparing the recombination temperatures (T_rec_) with the forbidden line temperatures (T_FL_), we conclude that {kappa}~20. While representing only a mild deviation from equilibrium, this result is sufficient to strongly influence abundances determined using methods that depend on measurements of the electron temperature from forbidden lines. We present a number of new emission line ratio diagnostics that cleanly separate the two parameters determining the optical spectrum of H II regions--the ionization parameter q or {} and the chemical abundance, 12+log(O/H). An automated code to extract these parameters is presented. Using the homogeneous data set from van Zee et al. 1998, Cat. J/AJ/116/2805, we find self-consistent results between all of these different diagnostics. The systematic errors between different line ratio diagnostics are much smaller than those found in the earlier strong-line work. Overall, the effect of the {kappa}-distribution on the strong-line abundances derived solely on the basis of theoretical models is rather small.

Identifier
DOI http://doi.org/10.26093/cds/vizier.22080010
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/ApJS/208/10
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/208/10
Related Identifier https://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/208/10
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/J/ApJS/208/10
Provenance
Creator Dopita M.A.; Sutherland R.S.; Nicholls D.C.; Kewley L.J.; Vogt F.P.A.
Publisher CDS
Publication Year 2013
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Representation
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Interdisciplinary Astronomy; Interstellar medium; Natural Sciences; Physics