THE NEXT GENERATION VIRGO CLUSTER SURVEY XVI: THE ANGULAR MOMENTUM OF DWARF EARLY-TYPE GALAXIES FROM GLOBULAR CLUSTER SATELLITES
- UCO/Lick Observatory, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States)
- Department of Astronomy, Peking University, Beijing 100871 (China)
- National Research Council of Canada, Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)
- European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748, Garching (Germany)
- Laboratoire d’Astrophysique de Marseille-LAM, Université d’Aix-Marseille and CNRS, UMR 7326, 38 rue F. Joliot-Curie, F-13388 Marseille Cedex 13 (France)
- CEA/IRFU/SAP, Laboratoire AIM Paris-Saclay, CNRS/INSU, Université Paris Diderot, Observatoire de Paris, PSL Research University, F-91191 Gif-sur-Yvette Cedex (France)
- Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Vicuna Mackenna 4860, 7820436 Macul, Santiago (Chile)
- Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)
We analyze the kinematics of six Virgo cluster dwarf early-type galaxies (dEs) from their globular cluster (GC) systems. We present new Keck/DEIMOS spectroscopy for three of them and re-analyze the data found in the literature for the remaining three. We use two independent methods to estimate the rotation amplitude ( V {sub rot}) and velocity dispersion ( σ {sub GC}) of the GC systems and evaluate their statistical significance by simulating non-rotating GC systems with the same number of GC satellites and velocity uncertainties. Our measured kinematics agree with the published values for the three galaxies from the literature and, in all cases, some rotation is measured. However, our simulations show that the null hypothesis of being non-rotating GC systems cannot be ruled out. In the case of VCC 1861, the measured V {sub rot} and the simulations indicate that it is not rotating. In the case of VCC 1528, the null hypothesis can be marginally ruled out, and thus it might be rotating although further confirmation is needed. In our analysis, we find that, in general, the measured V {sub rot} tends to be overestimated and the measured σ {sub GC} tends to be underestimated by amounts that depend on the intrinsic V {sub rot}/ σ {sub GC}, the number of observed GCs ( N {sub GC}), and the velocity uncertainties. The bias is negligible when N {sub GC} ≳ 20. In those cases where a large N {sub GC} is not available, it is imperative to obtain data with small velocity uncertainties. For instance, errors of ≤2 km s{sup −1} lead to V {sub rot} < 10 km s{sup −1} for a system that is intrinsically not rotating.
- OSTI ID:
- 22663069
- Journal Information:
- Astrophysical Journal, Vol. 822, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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