Morphological parameters of a Spitzer survey of stellar structure in galaxies



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Gil de Paz, Armando and ..., otros (2014) Morphological parameters of a Spitzer survey of stellar structure in galaxies. Astrophysical journal, 781 (1). ISSN 0004-637X

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The morphology of galaxies can be quantified to some degree using a set of scale-invariant parameters. Concentration (C), asymmetry (A), smoothness (S), the Gini index (G), the relative contribution of the brightest pixels to the second-order moment of the flux (M_20), ellipticity (E), and the Gini index of the second-order moment (G_M ) have all been applied to morphologically classify galaxies at various wavelengths. Here, we present a catalog of these parameters for the Spitzer Survey of stellar structure in Galaxies, a volume-limited, near-infrared (NIR) imaging survey of nearby galaxies using the 3.6 and 4.5 μm channels of the Infrared Array Camera on board the Spitzer Space Telescope. Our goal is to provide a reference catalog of NIR quantified morphology for high-redshift studies and galaxy evolution models with enough detail to resolve stellar mass morphology. We explore where normal, non-interacting galaxies—those typically found on the Hubble tuning fork—lie in this parameter space and show that there is a tight relation between concentration (C_82) and M_20 for normal galaxies. M_20 can be used to classify galaxies into earlier and later types (i.e., to separate spirals from irregulars). Several criteria using these parameters exist to select systems with a disturbed morphology, i.e., those that appear to be undergoing a tidal interaction. We examine the applicability of these criteria to Spitzer NIR imaging. We find that four relations, based on the parameters A and S, G and M_20, G_M, C, and M_20, respectively, select outliers in morphological parameter space, but each selects different subsets of galaxies. Two criteria (G_M > 0.6, G > –0.115 × M_20 + 0.384) seem most appropriate to identify possible mergers and the merger fraction in NIR surveys. We find no strong relation between lopsidedness and most of these morphological parameters, except for a weak dependence of lopsidedness on concentration and M_20.

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© 2014. The American Astronomical Society. All rights reserved. Artículo firmado por 24 autores. We thank the entire S^(4)G team for their efforts on this project and the anonymous referee for his or her insightful comments that improved the manuscript. The lead author thanks the European Space Agency for the support of the Research Fellowship program. This work was co-funded under the Marie Curie Actions of the European Commission (FP7-COFUND). We acknowledge financial support to the DAGAL network from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013/ under REA grant agreement number PITN-GA-2011-289313. E. A. and A. B. acknowledge the Centre National d'Etudes Spatiales (CNES, France) for financial support. They also acknowledge support from the FP7 Marie Curie Actions of the European Commission, via the Initial Training Network DAGAL under REA grant agreement 289313. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This research has made use of NASA's Astrophysics Data System. We acknowledge the usage of the HyperLEDA database (; Paturel et al. 2003).

Uncontrolled Keywords:H I Morphology; Digital-sky-survey; Polycyclic aromatic-hydrocarbons; High-redshift galaxies; Major merger fraction; Edge-on galaxies; Spiral galaxies; Seeing galaxies; Space-telescope; Nearby galaxies
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:34997
Deposited On:13 Jan 2016 17:00
Last Modified:10 Dec 2018 15:05

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