Published in

American Astronomical Society, Astrophysical Journal, 1(781), p. 12, 2013

DOI: 10.1088/0004-637x/781/1/12

Links

Tools

Export citation

Search in Google Scholar

Morphological Parameters of Aspitzersurvey of Stellar Structure in Galaxies

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

Full text: Download

Red circle
Preprint: archiving forbidden
Red circle
Postprint: archiving forbidden
Green circle
Published version: archiving allowed
Data provided by SHERPA/RoMEO

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 (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 mu m 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) \textgreater 0.6, G \textgreater -0.115 x 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.