Star clusters and black holes in galaxies across cosmic time Proceedings IAU Symposium No. 312, 2014 Y. Meiron, S. Li, F.-K. Liu & R. Spurzem, eds. c  International Astronomical Union 2016 doi:10.1017/S1743921315008005 Origin of ultra-compact dwarfs: a dynamical perspective Hong-Xin Zhang 1,2,3,4 , Eric W. Peng 1,2 ,PatrickCˆot´ e 5 , Chengze Liu 6,7 , Laura Ferrarese 5 , Jean-Charles Cuillandre 8 , Nelson Caldwell 9 , Stephen D. J. Gwyn 5 , Andr´ es Jord´ an 10 , Ariane Lan¸con 11 , Biao Li 1,2 , Roberto P. Mu˜ noz 10,11 , Thomas H. Puzia 10 , Kenji Bekki 12 , John Blakeslee 5 , Alessandro Boselli 13 , Michael J. Drinkwater 14 , Pierre-Alain Duc 15 , Patrick Durrell 16 , Eric Emsellem 17,18 , Peter Firth 14 and Ruben S´ anchez-Janssen 5 1 Department of Astronomy, Peking University, Beijing 100871, China email: hongxin@pku.edu.cn 2 Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China 3 CAS-CONICYT Fellow 4 Chinese Academy of Sciences South America Center for Astronomy, Camino EI Observatorio #1515, Las Condes, Santiago, Chile 5 National Research Council of Canada, Herzberg Astronomy and Astrophysics Program, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada 6 Center for Astronomy and Astrophysics, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China 7 Shanghai Key Lab for Particle Physics and Cosmology, Shanghai Jiao Tong University, Shanghai 200240, China 8 Canada–France–Hawaii Telescope Corporation, Kamuela, HI 96743, USA 9 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, 02138 10 Instituto de Astrof´ ısica, Facultad de F´ ısica, Pontificia Universidad Cat´ olica de Chile, Av. Vicu˜ na Mackenna 4860, 7820436 Macul, Santiago, Chile 11 Observatoire astronomique de Strasbourg, Universit´ e de Strasbourg, CNRS, UMR 7550, 11 rue de l’Universite, F-67000 Strasbourg, France 12 School of Physics, University of New South Wales, Sydney 2052, NSW, Australia 13 Aix Marseille Universit´ e, CNRS, LAM (Laboratoire d ′ Astrophysique de Marseille) UMR 7326, F-13388 Marseille, France 14 School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia 15 Laboratoire AIM Paris-Saclay, CNRS/INSU, Universit´ e Paris Diderot, CEA/IRFU/SAp, F-91191 Gif-sur-Yvette Cedex, France 16 Department of Physics & Astronomy, Youngstown State University, Youngstown, OH 44555 17 Universit´ e de Lyon 1, CRAL, Observatoire de Lyon, 9 av. Charles Andr´ e, F-69230 Saint-Genis Laval; CNRS, UMR 5574; ENS de Lyon, France 18 European Southern Observatory, Karl-Schwarzchild-Str. 2, D-85748 Garching, Germany Abstract. Discovery of ultra-compact dwarfs (UCDs) in the past 15 years blurs the once thought clear division between classic globular clusters (GCs) and early-type galaxies. The intermediate nature of UCDs, which are larger and more massive than typical GCs but more compact than typical dwarf galaxies, has triggered hot debate on whether UCDs should be considered galactic in origin or merely the most extreme GCs. Previous studies of various scaling relations, stellar populations and internal dynamics did not give an unambiguous answer to the primary origin of UCDs. In this contribution, we present the first ever detailed study of global dynamics of 97 264 https://www.cambridge.org/core/terms. https://doi.org/10.1017/S1743921315008005 Downloaded from https://www.cambridge.org/core. IP address: 18.206.13.133, on 17 Jun 2020 at 00:20:36, subject to the Cambridge Core terms of use, available at