Mon. Not. R. Astron. Soc., 453, 3729-3753 (2015/November-2)
Beyond Sersic + exponential disc morphologies in the Coma Cluster.
HEAD J.T.C.G., LUCEY J.R. and HUDSON M.J.
Abstract (from CDS):
Galaxies are not limited to simple spheroid or bulge + disc morphologies. We explore the diversity of internal galaxy structures in the Coma Cluster across a wide range of luminosities (-17 > Mg > -22) and cluster-centric radii (0 < rcluster < 1.3r200) through analysis of deep Canada-France-Hawaii Telescope i-band imaging. We present 2D multicomponent decomposition via galfit, encompassing a wide range of candidate model morphologies with up to three photometric components. Particular focus is placed on early-type galaxies with outer discs (i.e. S0s), and deviations from simple (`unbroken') exponential discs. Rigorous filtering ensures that each model component provides a statistically significant improvement to the goodness-of-fit. The majority of Coma Cluster members in our sample (478 of 631) are reliably fitted by symmetric structural models. Of these, 134 (28 percent) are single Sérsic objects, 143 (30 percent) are well-described by 2-component structures, while 201 (42 percent) require more complex models. Multicomponent Sérsic galaxies resemble compact pseudo-bulges (n ∼ 2, Re ∼ 4 kpc) surrounded by extended Gaussian-like outer structures (Re > 10 kpc). 11 percent of galaxies (N = 52) feature a break in their outer profiles, indicating `truncated' or `antitruncated' discs. Beyond the break radius, truncated galaxies are structurally consistent with exponential discs, disfavouring physical truncation as their formation mechanism. Bulge luminosity in antitruncated galaxies correlates strongly with galaxy luminosity, indicating a bulge-enhancing origin for these systems. Both types of broken disc are found overwhelmingly (>70 percent) in `barred' galaxies, despite a low measured bar fraction for Coma (20±2 percent). Thus, galaxy bars play an important role in formation of broken disc structures. No strong variation in galaxy structure is detected with projected cluster-centric radius.
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)
galaxies: clusters: individual: Abell 1656 - galaxies: elliptical and lenticular, cD - galaxies: evolution - galaxies: formation - galaxies: structure
VizieR on-line data:
<Available at CDS (J/MNRAS/453/3729): tablec1.dat>
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