THE GLOBULAR CLUSTER SYSTEM OF THE COMA CD GALAXY NGC 4874 FROM HUBBLE SPACE TELESCOPE ACS AND WFC3/IR IMAGING

Journal Article · Tue May 10 04:00:00 EDT 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/822/2/95· OSTI ID:22862954

Cho, Hyejeon; Jee, M. James; Lee, Young-Wook ^[1]; Blakeslee, John P. ^[2]; Chies-Santos, Ana L. ^[3]; Jensen, Joseph B. ^[4]

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1. Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 03722 (Korea, Republic of)
2. NRC Herzberg Astronomy and Astrophysics, Victoria, BC V9E 2E7 (Canada)
3. Departamento de Astronomia, Instituto de Física, UFRGS, Porto Alegre, R.S. 91501-970 (Brazil)
4. Department of Physics, Utah Valley University, Orem, Utah 84058 (United States)

We present new Hubble Space Telescope (HST) optical and near-infrared (NIR) photometry of the rich globular cluster (GC) system NGC 4874, the cD galaxy in the core of the Coma cluster (Abell 1656). NGC 4874 was observed with the HST Advanced Camera for Surveys in the F475W (g {sub 475}) and F814W (I {sub 814}) passbands and with the Wide Field Camera 3 IR Channel in F160W (H {sub 160}). The GCs in this field exhibit a bimodal optical color distribution with more than half of the GCs falling on the red side at g {sub 475}−I {sub 814} > 1. Bimodality is also present, though less conspicuously, in the optical-NIR I {sub 814}−H {sub 160} color. Consistent with past work, we find evidence for nonlinearity in the g {sub 475}−I {sub 814} versus I {sub 814}−H {sub 160} color–color relation. Our results thus underscore the need for understanding the detailed form of the color–metallicity relations in interpreting observational data on GC bimodality. We also find a very strong color–magnitude trend, or “blue tilt,” for the blue component of the optical color distribution of the NGC 4874 GC system. A similarly strong trend is present for the overall mean I {sub 814}−H {sub 160} color as a function of magnitude; for M {sub 814} < −10 mag, these trends imply a steep mass–metallicity scaling with Z∝M{sub GC}{sup 1.4±0.4}, but the scaling is not a simple power law and becomes much weaker at lower masses. As in other similar systems, the spatial distribution of the blue GCs is more extended than that of the red GCs, partly because of blue GCs associated with surrounding cluster galaxies. In addition, the center of the GC system is displaced by 4 ± 1 kpc toward the southwest from the luminosity center of NGC 4874, in the direction of NGC 4872. Finally, we remark on a dwarf elliptical galaxy with a noticeably asymmetrical GC distribution. Interestingly, this dwarf has a velocity of nearly −3000 km s{sup −1} with respect to NGC 4874; we suggest it is on its first infall into the cluster core and is undergoing stripping of its GC system by the cluster potential.

• OSTI ID: 22862954
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 822; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
GALAXIES
GALAXY CLUSTERS
LUMINOSITY
MASS
METALLICITY
PHOTOMETRY
SPACE
SPATIAL DISTRIBUTION
STAR CLUSTERS
TELESCOPES
VELOCITY