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Origin of ultra-compact dwarfs: a dynamical perspective

Published online by Cambridge University Press:  07 March 2016

Hong-Xin Zhang ,
Eric W. Peng ,
Patrick Côté ,
Chengze Liu ,
Laura Ferrarese ,
Jean-Charles Cuillandre ,
Nelson Caldwell ,
Stephen D. J. Gwyn ,
Andrés Jordán  and
Ariane Lançon
...Show all authors
Hong-Xin Zhang
Affiliation:
Department of Astronomy, Peking University, Beijing 100871, China email: hongxin@pku.edu.cn Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China CAS-CONICYT Fellow Chinese Academy of Sciences South America Center for Astronomy, Camino EI Observatorio #1515, Las Condes, Santiago, Chile
Eric W. Peng
Affiliation:
Department of Astronomy, Peking University, Beijing 100871, China email: hongxin@pku.edu.cn Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China
Patrick Côté
Affiliation:
National Research Council of Canada, Herzberg Astronomy and Astrophysics Program, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
Chengze Liu
Affiliation:
Center for Astronomy and Astrophysics, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China Shanghai Key Lab for Particle Physics and Cosmology, Shanghai Jiao Tong University, Shanghai 200240, China
Laura Ferrarese
Affiliation:
National Research Council of Canada, Herzberg Astronomy and Astrophysics Program, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
Jean-Charles Cuillandre
Affiliation:
Canada–France–Hawaii Telescope Corporation, Kamuela, HI 96743, USA
Nelson Caldwell
Affiliation:
Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, 02138
Stephen D. J. Gwyn
Affiliation:
National Research Council of Canada, Herzberg Astronomy and Astrophysics Program, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
Andrés Jordán
Affiliation:
Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile
Ariane Lançon
Affiliation:
Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l'Universite, F-67000 Strasbourg, France
Biao Li
Affiliation:
Department of Astronomy, Peking University, Beijing 100871, China email: hongxin@pku.edu.cn Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China
Roberto P. Muñoz
Affiliation:
Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l'Universite, F-67000 Strasbourg, France
Thomas H. Puzia
Affiliation:
Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile
Kenji Bekki
Affiliation:
School of Physics, University of New South Wales, Sydney 2052, NSW, Australia
John Blakeslee
Affiliation:
National Research Council of Canada, Herzberg Astronomy and Astrophysics Program, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
Alessandro Boselli
Affiliation:
Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, F-13388 Marseille, France
Michael J. Drinkwater
Affiliation:
School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
Pierre-Alain Duc
Affiliation:
Laboratoire AIM Paris-Saclay, CNRS/INSU, Université Paris Diderot, CEA/IRFU/SAp, F-91191 Gif-sur-Yvette Cedex, France
Patrick Durrell
Affiliation:
Department of Physics & Astronomy, Youngstown State University, Youngstown, OH 44555
Eric Emsellem
Affiliation:
Université de Lyon 1, CRAL, Observatoire de Lyon, 9 av. Charles André, F-69230 Saint-Genis Laval; CNRS, UMR 5574; ENS de Lyon, France European Southern Observatory, Karl-Schwarzchild-Str. 2, D-85748 Garching, Germany
Peter Firth
Affiliation:
School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
Ruben Sánchez-Janssen
Affiliation:
National Research Council of Canada, Herzberg Astronomy and Astrophysics Program, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
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Abstract

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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 UCDs (rh ≳ 10 pc) associated with the central cD galaxy of the Virgo cluster, M87. We found that UCDs follow a different radial number density profile and different rotational properties from GCs. The orbital anisotropies of UCDs are tangentially-biased within ~ 40 kpc of M87 and become radially-biased with radius further out. In contrast, the blue GCs, which have similar median colors to our sample of UCDs, become more tangentially-biased at larger radii beyond ~ 40 kpc. Our analysis suggests that most UCDs in M87 are not consistent with being merely the most luminous and extended examples of otherwise normal GCs. The radially-biased orbital structure of UCDs at large radii is in general agreement with the scenario that most UCDs originated from the tidally threshed dwarf galaxies.

Keywords

galaxies: clustersglobular clustersgalaxies: nucleigalaxies: elliptical and lenticularcDgalaxies: kinematics and dynamics
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 10 , Issue S312: Star Clusters and Black Holes in Galaxies across Cosmic Time , August 2014 , pp. 264 - 268
Copyright
Copyright © International Astronomical Union 2016 

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