SCYON Abstract

Received on: 06 09 2018

The Next Generation Virgo Cluster Survey (NGVS). XXXI. The Kinematics of Intracluster Globular Clusters in the Core of the Virgo Cluster

Authors:A. Longobardi 1, E. W. Peng 2,1, P. Côté 3, and 21 co-authors
Affiliations:(1) Kavli Institute for Astronomy and Astrophysics, Peking University; (2) Department of Astronomy, Peking University; (3) Herzberg Astronomy and Astrophysics Research Centre, National Research Council of Canada
Accepted by: Astrophysical Journal

Intracluster (IC) populations are expected to be a natural result of the hierarchical assembly of clusters, yet their low space densities make them difficult to detect and study. We present the first definitive kinematic detection of an IC population of globular clusters (GCs) in the Virgo cluster, around the central galaxy M87. This study focuses on the Virgo core, for which the combination of Next Generation Virgo Cluster Survey photometry and follow-up spectroscopy allows us to reject foreground star contamination and explore GC kinematics over the full Virgo dynamical range. The GC kinematics changes gradually with galactocentric distance, decreasing in mean velocity and increasing in velocity dispersion, eventually becoming indistinguishable from t he kinematics of Virgo dwarf galaxies at R > 320 kpc. By kinematically tagging M87 halo and intracluster GCs, we find that (1) the M87 halo has a smaller fraction ($52\pm3$%) of blue clusters with respect to the IC counterpart (77 ± 10%), (2) the $(g'‑r')_0$ versus $(i'‑z')_0$ color–color diagrams reveal a galaxy population that is redder than the IC population, which may be due to a different composition in chemical abundance and progenitor mass, and (3) the ICGC distribution is shallower and more extended than the M87 GCs, yet still centrally concentrated. The ICGC specific frequency, $S_{N,ICL} = 10.2\pm4.8$, is consistent with what is observed for the population of quenched, low-mass galaxies within 1 Mpc from the cluster’s center. The IC population at Virgo’s center is thus consistent with being an accreted component from low-mass galaxies tidally stripped or disrupted through interactions, with a total mass of $M_{ICL,tot}=10.8\pm0.1\times 10^{11}M_\odot$.

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