期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 480, 期 1, 页码 251-260出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/sty1748
关键词
galaxies: dwarf; galaxies: evolution; galaxies: individual: Sextans dSph; Local Group; galaxies: structure; dark matter
资金
- Fundacion la Caixa
- Spanish Ministry of Economy and Competitiveness (MINECO) under the Ramon y Cajal Programme [RYC-2012-11537]
- Spanish Ministry of Economy and Competitiveness (MINECO) [AYA2014-56795-P]
- DOE (USA)
- NSF (USA)
- MISE (Spain)
- STFC (UK)
- HEFCE (UK)
- NCSA (UIUC)
- KICP (U. Chicago)
- CCAPP (Ohio State)
- MIFPA (Texas AM)
- CNPQ (Brazil)
- FAPERJ (Brazil)
- FINEP (Brazil)
- MINECO (Spain)
- DFG (Germany)
- Argonne Lab
- UC Santa Cruz
- University of Cambridge
- CIEMAT-Madrid
- University of Chicago
- University College London
- DES-Brazil Consortium
- University of Edinburgh
- ETH Zurich
- Fermilab
- University of Illinois
- ICE (IEEC-CSIC)
- IFAE Barcelona
- Lawrence Berkeley Lab
- LMU Munchen
- associated Excellence Cluster Universe
- University of Michigan
- NOAO
- University of Nottingham
- Ohio State University
- University of Pennsylvania
- University of Portsmouth
- SLAC National Lab
- Stanford University
- University of Sussex
- Texas AM University
We report the discovery of clear observational signs of past accretion/merger events in one of the Milky Way satellite galaxies, the Sextans dwarf spheroidal (dSph). These were uncovered in the spatial distribution, internal kinematics, and metallicity properties of Sextans stars using literature CTIO/DECam photometric and Magellan/MMFS spectroscopic catalogues. We find the spatial distribution of stars to vary as a function of the colour/metallicity, being rather regular and round for the blue (metal-poor) red giant branch and main-sequence turn-off stars but much more elliptical and irregularly shaped for the red (metal-rich) ones, with a distinct 'shell-like' overdensity in the northeast side. We also detect kinematic anomalies, in the form of a 'ring-like' feature with a considerably larger systemic line-of-sight velocity and lower metallicity than the rest of stars; even the photometrically selected component with a regular looking spatial distribution displays complex kinematics. With a stellar mass of just similar to 5 x 10(5) M-circle dot, Sextans becomes the smallest galaxy presenting clear observational signs of accretion to date.
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