IZI: Inferring the gas phase metallicity (z) and ionization parameter (q) of ionized nebulae using bayesian statistics
Author
dc.contributor.author
Blanc Mendiberri, Guillermo
Admission date
dc.date.accessioned
2015-05-19T18:03:46Z
Available date
dc.date.available
2015-05-19T18:03:46Z
Publication date
dc.date.issued
2015-01-10
Cita de ítem
dc.identifier.citation
The Astrophysical Journal, 798:99 (21pp), 2015 January 10
en_US
Identifier
dc.identifier.other
doi:10.1088/0004-637X/798/2/99
Identifier
dc.identifier.uri
https://repositorio.uchile.cl/handle/2250/130639
General note
dc.description
Artículo de publicación ISI
en_US
Abstract
dc.description.abstract
We present a new method for inferring the metallicity (Z) and ionization parameter (q) of H ii regions and
star-forming galaxies using strong nebular emission lines (SELs). We use Bayesian inference to derive the joint
and marginalized posterior probability density functions for Z and q given a set of observed line fluxes and an input
photoionization model. Our approach allows the use of arbitrary sets of SELs and the inclusion of flux upper limits.
The method provides a self-consistent way of determining the physical conditions of ionized nebulae that is not tied
to the arbitrary choice of a particular SEL diagnostic and uses all the available information. Unlike theoretically
calibrated SEL diagnostics, the method is flexible and not tied to a particular photoionization model. We describe
our algorithm, validate it against other methods, and present a tool that implements it called IZI. Using a sample
of nearby extragalactic H ii regions, we assess the performance of commonly used SEL abundance diagnostics.
We also use a sample of 22 local H ii regions having both direct and recombination line (RL) oxygen abundance
measurements in the literature to study discrepancies in the abundance scale between different methods. We find
that oxygen abundances derived through Bayesian inference using currently available photoionization models in
the literature can be in good (∼30%) agreement with RL abundances, although some models perform significantly
better than others. We also confirm that abundances measured using the direct method are typically ∼0.2 dex lower
than both RL and photoionization-model-based abundances.