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QUANTIFYING KINEMATIC SUBSTRUCTURE IN THE MILKY WAY'S STELLAR HALO
Xue, Xiang-Xiang1,2; Rix, Hans-Walter2; Yanny, Brian3; Beers, Timothy C.4,14; Bell, Eric F.2,5; Zhao, Gang1; Bullock, James S.6; Johnston, Kathryn V.7; Morrison, Heather8; Rockosi, Constance9; Koposov, Sergey E.2,10,11; Kang, Xi2,12; Liu, Chao2; Luo, Ali1; Lee, Young Sun4; Weaver, Benjamin A.13
2011-09-01
Source PublicationASTROPHYSICAL JOURNAL
Volume738Issue:1
AbstractWe present and analyze the positions, distances, and radial velocities for over 4000 blue horizontal-branch (BHB) stars in the Milky Way's halo, drawn from SDSS DR8. We search for position-velocity substructure in these data, a signature of the hierarchical assembly of the stellar halo. Using a cumulative "close pair distribution" as a statistic in the four-dimensional space of sky position, distance, and velocity, we quantify the presence of position-velocity substructure at high statistical significance among the BHB stars: pairs of BHB stars that are close in position on the sky tend to have more similar distances and radial velocities compared to a random sampling of these overall distributions. We make analogous mock observations of 11 numerical halo formation simulations, in which the stellar halo is entirely composed of disrupted satellite debris, and find a level of substructure comparable to that seen in the actually observed BHB star sample. This result quantitatively confirms the hierarchical build-up of the stellar halo through a signature in phase (position-velocity) space. In detail, the structure present in the BHB stars is somewhat less prominent than that seen in most simulated halos, quite possibly because BHB stars represent an older sub-population. BHB stars located beyond 20 kpc from the Galactic center exhibit stronger substructure than at r(gc) < 20 kpc.
KeywordGalaxies: Individual (Milkyway) Galaxy: Halo Galaxy: Structure Stars: Horizontal-branch Stars: Kinematics And Dynamics
DOI10.1088/0004-637X/738/1/79
Indexed BySCI
Language英语
WOS IDWOS:000294015500079
Citation statistics
Document Type期刊论文
Identifierhttp://ir.bao.ac.cn/handle/114a11/7882
Collection光学天文研究部
Affiliation1.Chinese Acad Sci, Key Lab Opt Astron, Natl Astron Observ, Beijing 100012, Peoples R China
2.Max Planck Inst Astron, D-69117 Heidelberg, Germany
3.Fermilab Natl Accelerator Lab, Batavia, IL 60510 USA
4.Michigan State Univ, Dept Phys & Astron, E Lansing, MI 48824 USA
5.Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA
6.Univ Calif Irvine, Ctr Cosmol, Dept Phys & Astron, Irvine, CA 92697 USA
7.Columbia Univ, Dept Astron, New York, NY 10027 USA
8.Case Western Reserve Univ, Dept Astron, Cleveland, OH 44106 USA
9.Univ Calif Santa Cruz, Lick Observ, Santa Cruz, CA 95060 USA
10.Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England
11.Moscow MV Lomonosov State Univ, Sternberg Astron Inst, Moscow 119992, Russia
12.Chinese Acad Sci, Purple Mt Observ, Nanjing 210008, Peoples R China
13.NYU, Ctr Cosmol & Particle Phys, New York, NY 10003 USA
14.Michigan State Univ, JINA Joint Inst Nucl Astrophys, E Lansing, MI 48824 USA
Recommended Citation
GB/T 7714
Xue, Xiang-Xiang,Rix, Hans-Walter,Yanny, Brian,et al. QUANTIFYING KINEMATIC SUBSTRUCTURE IN THE MILKY WAY'S STELLAR HALO[J]. ASTROPHYSICAL JOURNAL,2011,738(1).
APA Xue, Xiang-Xiang.,Rix, Hans-Walter.,Yanny, Brian.,Beers, Timothy C..,Bell, Eric F..,...&Weaver, Benjamin A..(2011).QUANTIFYING KINEMATIC SUBSTRUCTURE IN THE MILKY WAY'S STELLAR HALO.ASTROPHYSICAL JOURNAL,738(1).
MLA Xue, Xiang-Xiang,et al."QUANTIFYING KINEMATIC SUBSTRUCTURE IN THE MILKY WAY'S STELLAR HALO".ASTROPHYSICAL JOURNAL 738.1(2011).
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