Morphological parameters of a spitzer survey of stellar structure in galaxies

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

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

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 (M20), 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 (C82) and M20 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 M20, GM, C, and M20, respectively, select outliers in morphological parameter space, but each selects different subsets of galaxies. Two criteria (GM > 0.6, G >-0.115 × M20 + 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 M20.

Original languageEnglish (US)
Article number12
JournalAstrophysical Journal
Volume781
Issue number1
DOIs
StatePublished - Jan 20 2014

Keywords

  • galaxies: elliptical and lenticular, cD
  • galaxies: general
  • galaxies: irregular
  • galaxies: spiral
  • galaxies: statistics
  • galaxies: stellar content
  • galaxies: structure

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Holwerda, B. W., Muñoz-Mateos, J. C., Comerón, S., Meidt, S., Sheth, K., Laine, S., Hinz, J. L., Regan, M. W., Gil De Paz, A., Menéndez-Delmestre, K., Seibert, M., Kim, T., Mizusawa, T., Laurikainen, E., Salo, H., Laine, J., Gadotti, D. A., Zaritsky, D., Erroz-Ferrer, S., ... Pirzkal, N. (2014). Morphological parameters of a spitzer survey of stellar structure in galaxies. Astrophysical Journal, 781(1), [12]. https://doi.org/10.1088/0004-637X/781/1/12