Bibcode
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.
Bibliographical reference
The Astrophysical Journal, Volume 781, Issue 1, article id. 12, 19 pp. (2014).
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1
2014
Journal
Citations
31
Refereed citations
30
Description
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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