Classifying Intermediate Redshift Galaxies in SDSS: Alternative Diagnostic Diagrams

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Autori principali: Feuillet, Léa, Meléndez, Marcio, Kraemer, Steve, Schmitt, Henrique, Fischer, Travis, Reeves, James
Natura: Preprint
Pubblicazione: 2023
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author Feuillet, Léa
Meléndez, Marcio
Kraemer, Steve
Schmitt, Henrique
Fischer, Travis
Reeves, James
author_facet Feuillet, Léa
Meléndez, Marcio
Kraemer, Steve
Schmitt, Henrique
Fischer, Travis
Reeves, James
contents We select a sample of 1,437 active galactic nuclei (AGN) from the catalog of the Sloan Digital Sky Survey (SDSS) galaxy properties from the Portsmouth group by detection of the high-ionization [Ne V] 3426 Å emission line. We compare the fluxes of [Ne III] 3869 Å, [O III] 5007 Å, [O II] 3726, 3728 Å, and [O I] 6300 Å to that of [Ne V]. All four lines show a strong linear correlation with [Ne V], although lines from ions with lower ionization potentials have a lower correlation coefficient. We investigate the use of two forbidden-line ratio (FLR) diagnostic diagrams that do not rely on H$α$ in order to classify high redshift galaxies. These use the [Ne III]/[O II] line ratio plotted against [O III]/[O I] and [O III]/[O II] respectively. We use photo-ionization modeling to characterize the behavior of the narrow-line region in AGN and star-forming regions and test the validity of our diagnostic diagrams. We also use a luminosity cutoff of log L[OIII] [erg/s] = 42, which lowers the contamination of the AGN region by star-forming galaxies down to 10% but does not remove Green Pea and Purple Grape galaxies from the AGN region. We also investigate the OHNO diagram which uses [Ne III]/[O II] plotted against [O III]/H$β$. Using our new diagnostic diagrams, we are able to reliably classify AGN up to a redshift of z $\leq$ 1.06, and add more than 822 new AGN to the [Ne V]-selected AGN sample.
format Preprint
id arxiv_https___arxiv_org_abs_2312_17381
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Classifying Intermediate Redshift Galaxies in SDSS: Alternative Diagnostic Diagrams
Feuillet, Léa
Meléndez, Marcio
Kraemer, Steve
Schmitt, Henrique
Fischer, Travis
Reeves, James
Astrophysics of Galaxies
We select a sample of 1,437 active galactic nuclei (AGN) from the catalog of the Sloan Digital Sky Survey (SDSS) galaxy properties from the Portsmouth group by detection of the high-ionization [Ne V] 3426 Å emission line. We compare the fluxes of [Ne III] 3869 Å, [O III] 5007 Å, [O II] 3726, 3728 Å, and [O I] 6300 Å to that of [Ne V]. All four lines show a strong linear correlation with [Ne V], although lines from ions with lower ionization potentials have a lower correlation coefficient. We investigate the use of two forbidden-line ratio (FLR) diagnostic diagrams that do not rely on H$α$ in order to classify high redshift galaxies. These use the [Ne III]/[O II] line ratio plotted against [O III]/[O I] and [O III]/[O II] respectively. We use photo-ionization modeling to characterize the behavior of the narrow-line region in AGN and star-forming regions and test the validity of our diagnostic diagrams. We also use a luminosity cutoff of log L[OIII] [erg/s] = 42, which lowers the contamination of the AGN region by star-forming galaxies down to 10% but does not remove Green Pea and Purple Grape galaxies from the AGN region. We also investigate the OHNO diagram which uses [Ne III]/[O II] plotted against [O III]/H$β$. Using our new diagnostic diagrams, we are able to reliably classify AGN up to a redshift of z $\leq$ 1.06, and add more than 822 new AGN to the [Ne V]-selected AGN sample.
title Classifying Intermediate Redshift Galaxies in SDSS: Alternative Diagnostic Diagrams
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2312.17381