Morphological Parameters of a Spitzer Survey of Stellar Structure in Galaxies

Holwerda, B. W.; Muñoz-Mateos, J.-C.; Pirzkal, N.; Bosma, A.; Athanassoula, E.; Knapen, J. H.; Ho, L. C.; Erroz-Ferrer, S.; Zaritsky, D.; Gadotti, D. A.; Laine, J.; Salo, H.; Mizusawa, T.; Laurikainen, E.; Kim, T.; Seibert, M.; Menéndez-Delmestre, K.; Gil de Paz, A.; Sheth, K.; Meidt, S.; Comerón, S.; Regan, M. W.; Laine, S.; Hinz, J. L.
Referencia bibliográfica

The Astrophysical Journal, Volume 781, Issue 1, article id. 12, 19 pp. (2014).

Fecha de publicación:
1
2014
Número de autores
24
Número de autores del IAC
2
Número de citas
31
Número de citas referidas
30
Descripción
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 (GM ) 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, GM , C, and M 20, respectively, select outliers in morphological parameter space, but each selects different subsets of galaxies. Two criteria (GM > 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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