Stellar Population Properties of Ultracompact Dwarfs in M87: A Mass–Metallicity Correlation Connecting Low-metallicity Globular Clusters and Compact Ellipticals

doi:10.3847/1538-4357/aab88a

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	Stellar Population Properties of Ultracompact Dwarfs in M87: A Mass–Metallicity Correlation Connecting Low-metallicity Globular Clusters and Compact Ellipticals
	Zhang,Hong-Xin 1,2; Puzia,Thomas H.1; Peng,Eric W.3,4; Liu,Chengze 5,6; C?té,Patrick 7; Ferrarese,Laura 7; Duc,Pierre-Alain 8; Eigenthaler,Paul 1; Lim,Sungsoon 3,4; Lan?on,Ariane 9
刊名	The Astrophysical Journal
	2018-05-03
卷号	858 期号:1
关键词	galaxies: clusters: individual (Virgo) galaxies: dwarf galaxies: formation galaxies: star clusters: general galaxies: stellar content globular clusters: general
ISSN号	0004-637X
DOI	10.3847/1538-4357/aab88a
英文摘要	Abstract We derive stellar population parameters for a representative sample of ultracompact dwarfs (UCDs) and a large sample of massive globular clusters (GCs) with stellar masses ? 106 M⊙ in the central galaxy M87 of the Virgo galaxy cluster, based on model fitting to the Lick-index measurements from both the literature and new observations. After necessary spectral stacking of the relatively faint objects in our initial sample of 40 UCDs and 118 GCs, we obtain 30 sets of Lick-index measurements for UCDs and 80 for GCs. The M87 UCDs have ages ? 8 Gyr and [α/Fe]???0.4 dex, in agreement with previous studies based on smaller samples. The literature UCDs, located in lower-density environments than M87, extend to younger ages and smaller [α/Fe] (at given metallicities) than M87 UCDs, resembling the environmental dependence of the stellar nuclei of dwarf elliptical galaxies (dEs) in the Virgo cluster. The UCDs exhibit a positive mass–metallicity relation (MZR), which flattens and connects compact ellipticals at stellar masses ? 108 M⊙. The Virgo dE nuclei largely follow the average MZR of UCDs, whereas most of the M87 GCs are offset toward higher metallicities for given stellar masses. The difference between the mass–metallicity distributions of UCDs and GCs may be qualitatively understood as a result of their different physical sizes at birth in a self-enrichment scenario or of galactic nuclear cluster star formation efficiency being relatively low in a tidal stripping scenario for UCD formation.?The existing observations provide the necessary but not sufficient evidence for tidally stripped dE nuclei being the dominant contributors to the M87 UCDs.
语种	英语
出版者	The American Astronomical Society
WOS记录号	IOP:0004-637X-858-1-AAB88A
内容类型	期刊论文
源URL	[http://ir.bao.ac.cn/handle/114a11/35570]
专题	中国科学院国家天文台
作者单位	1.Institute of Astrophysics, Pontificia Universidad Católica de Chile, Av. Vicu?a Mackenna 4860, 7820436 Macul, Santiago, Chile; zhhxin@gmail.com 2.CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei 230026, People’s Republic of China 3.Department of Astronomy, Peking University, Beijing 100871, People’s Republic of China 4.Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People’s Republic of China 5.Department of Astronomy, Shanghai Key Laboratory for Particle Physics and Cosmology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China 6.Shanghai Key Lab for Particle Physics and Cosmology, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China 7.NRC Herzberg Astronomy and Astrophysics Research Centre, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada 8.Université de Strasbourg, CNRS, Observatoire astronomique de Strasbourg, UMR 7550, F-67000 Strasbourg, France 9.Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l’Universite, F-67000 Strasbourg, France 10.NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
推荐引用方式 GB/T 7714	Zhang,Hong-Xin,Puzia,Thomas H.,Peng,Eric W.,et al. Stellar Population Properties of Ultracompact Dwarfs in M87: A Mass–Metallicity Correlation Connecting Low-metallicity Globular Clusters and Compact Ellipticals[J]. The Astrophysical Journal,2018,858(1).
APA	Zhang,Hong-Xin.,Puzia,Thomas H..,Peng,Eric W..,Liu,Chengze.,C?té,Patrick.,...&Yu,Jincheng.(2018).Stellar Population Properties of Ultracompact Dwarfs in M87: A Mass–Metallicity Correlation Connecting Low-metallicity Globular Clusters and Compact Ellipticals.The Astrophysical Journal,858(1).
MLA	Zhang,Hong-Xin,et al."Stellar Population Properties of Ultracompact Dwarfs in M87: A Mass–Metallicity Correlation Connecting Low-metallicity Globular Clusters and Compact Ellipticals".The Astrophysical Journal 858.1(2018).