Bibcode
Kalinova, V.; Colombo, D.; Rosolowsky, E.; Kannan, R.; Galbany, L.; García-Benito, R.; González Delgado, R.; Sánchez, S. F.; Ruiz-Lara, T.; Méndez-Abreu, J.; Catalán-Torrecilla, C.; Sánchez-Menguiano, L.; de Lorenzo-Cáceres, A.; Costantin, L.; Florido, E.; Kodaira, K.; Marino, R. A.; Läsker, R.; Bland-Hawthorn, J.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 469, Issue 3, p.2539-2594
Advertised on:
8
2017
Citations
35
Refereed citations
33
Description
We present a galaxy classification system for 238 (E1-Sdm) CALIFA (Calar
Alto Legacy Integral Field Area) galaxies based on the shapes and
amplitudes of their circular velocity curves (CVCs). We infer the CVCs
from the de-projected surface brightness of the galaxies, after scaling
by a constant mass-to-light ratio based on stellar dynamics - solving
axisymmetric Jeans equations via fitting the second velocity moment
V_{rms}=√{V^2+σ ^2} of the stellar kinematics. We use
principal component analysis (PCA) applied to the CVC shapes to find
characteristic features and use a k-means classifier to separate
circular curves into classes. This objective classification method
identifies four different classes, which we name slow-rising (SR), flat
(FL), round-peaked (RP) and sharp-peaked (SP) circular curves. SR are
typical for low-mass, late-type (Sb-Sdm), young, faint, metal-poor and
disc-dominated galaxies. SP are typical for high-mass, early-type
(E1-E7), old, bright, metal-rich and bulge-dominated galaxies. FL and RP
appear presented by galaxies with intermediate mass, age, luminosity,
metallicity, bulge-to-disc ratio and morphologies (E4-S0a, Sa-Sbc). The
discrepancy mass factor, fd = 1 -
M*/Mdyn, have the largest value for SR and SP
classes (˜ 74 per cent and ˜ 71 per cent, respectively) in
contrast to the FL and RP classes (with ˜ 59 per cent and ˜
61 per cent, respectively). Circular curve classification presents an
alternative to typical morphological classification and appears more
tightly linked to galaxy evolution.
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