Astrophys. J., 869, 145-145 (2018/December-3)
A 3D Voronoi+Gapper galaxy cluster finder in Redshift space to z ∼ 0.2. II. An abundant cluster population dominated by late-type galaxies unveiled.
CAMPUSANO L.E., MARINELLO G., CLOWES R.G., HAINES C.P., PEREIRA S., PIZARRO D., HITSCHFELD-KAHLER N. and SOCHTING I.K.
Abstract (from CDS):
We identify 1901 galaxy clusters (Ng >= 2) with the VoML+G algorithm (Paper I) on the Two-Degree Field Galaxy Redshift Survey. We present the 341 clusters with at least 10 galaxies that are within 0.009 < z < 0.14 (the Catalog), of which 254 (∼75%) have counterparts in the literature (NED), with the remainder (87) plausibly "new" because of incompleteness of previous searches or unusual galaxy contents. The 207 clusters within z = 0.04-0.09 are used to study the properties of the galaxy systems in the nearby universe, including their galaxy contents parameterized by the late-type galaxy fractions (fL). For this nearly complete cluster subsample, we find the following: (i) 63% are dominated by early-type galaxies (i.e., the late-type-poor clusters, fL < 0.5) with corresponding mean multiplicity and logarithmic virial mass (in units of M☉) of 22 ± 1 and 12.91 ± 0.04, respectively; and (ii) 37% are dominated by late-type galaxies (i.e., the late-type-rich clusters, fL >= 0.5) with corresponding mean multiplicity and logarithmic virial mass (in units of M☉) of 15.7 ± 0.9 and 12.66 ± 0.07, respectively. The statistical analysis of the late-type fraction distribution supports, with a 3σ confidence level, the presence of two population components. It is suggested that the late-type-poor galaxy systems reflect and extend the class of Abell-APM-EDCC clusters and that the late-type-rich systems (∼one-third of the total) belong to a new, previously unappreciated class. The late-type-rich clusters, on average high mass-to-light ratio systems, appear to be more clustered on large scales than the late-type-poor clusters. A class of late-type-rich clusters is not predicted by current theory.
© 2018. The American Astronomical Society.
cosmology: observations - galaxies: clusters: general - large-scale structure of universe - methods: data analysis
VizieR on-line data:
<Available at CDS (J/ApJ/869/145): table2.dat>
Table 2: [CMC2018b] NNN (Nos 1-341).
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