The First Tidally Disrupted Ultra-faint Dwarf Galaxy?: A Spectroscopic Analysis of the Tucana III Stream

被引：52

作者：

Li, T. S. ^{[1
,2
]}

Simon, J. D. ^{[3
]}

Kuehn, K. ^{[4
]}

Pace, A. B. ^{[5
,6
]}

Erkal, D. ^{[7
,8
]}

Bechtol, K. ^{[9
]}

Yanny, B. ^{[1
]}

Drlica-Wagner, A. ^{[1
]}

Marshall, J. L. ^{[5
,6
]}

Lidman, C. ^{[4
,10
]}

Balbinot, E. ^{[7
]}

Carollo, D. ^{[11
]}

Jenkins, S. ^{[2
]}

Martinez-Vazquez, C. E. ^{[12
]}

Shipp, N. ^{[2
]}

Stringer, K. M. ^{[5
,6
]}

Vivas, A. K. ^{[12
]}

Walker, A. R. ^{[12
]}

Wechsler, R. H. ^{[13
,14
,15
]}

Abdalla, F. B. ^{[16
,17
]}

Allam, S. ^{[1
]}

Annis, J. ^{[1
]}

Avila, S. ^{[18
]}

Bertin, E. ^{[19
,20
]}

Brooks, D. ^{[16
]}

Buckley-Geer, E. ^{[1
]}

Burke, D. L. ^{[14
,15
]}

Carnero Rosell, A. ^{[21
,22
]}

Kind, M. Carrasco ^{[23
,24
]}

Carretero, J. ^{[25
]}

Cunha, C. E. ^{[14
]}

D'Andrea, C. B. ^{[26
]}

da Costa, L. N. ^{[21
,22
]}

Davis, C. ^{[14
]}

De Vicente, J. ^{[27
]}

Doel, P. ^{[16
]}

Eifler, T. F. ^{[28
,29
]}

Evrard, A. E. ^{[30
,31
]}

Flaugher, B. ^{[1
]}

Frieman, J. ^{[1
,2
]}

Garcia-Bellido, J. ^{[32
]}

Gaztanaga, E. ^{[33
,34
]}

Gerdes, D. W. ^{[30
,31
]}

Gruen, D. ^{[14
,15
]}

Gruendl, R. A. ^{[23
,24
]}

Gschwend, J. ^{[21
,22
]}

Gutierrez, G. ^{[1
]}

Hartley, W. G. ^{[16
,35
]}

Hollowood, D. L. ^{[36
]}

Honscheid, K. ^{[37
,38
]}

机构：

[1] Fermilab Natl Accelerator Lab, POB 500, Batavia, IL 60510 USA

[2] Univ Chicago, Kavli Inst Cosmol Phys, Chicago, IL 60637 USA

[3] Observ Carnegie Inst Sci, 813 Santa Barbara St, Pasadena, CA 91101 USA

[4] Australian Astron Observ, N Ryde, NSW 2113, Australia

[5] Texas A&M Univ, George P & Cynthia Woods Mitchell Inst Fundamenta, College Stn, TX 77843 USA

[6] Texas A&M Univ, Dept Phys & Astron, College Stn, TX 77843 USA

[7] Univ Surrey, Dept Phys, Guildford GU2 7XH, Surrey, England

[8] Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England

[9] LSST, 933 North Cherry Ave, Tucson, AZ 85721 USA

[10] Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2601, Australia

[11] INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy

[12] Natl Opt Astron Observ, Cerro Tololo Inter Amer Observ, Casilla 603, La Serena, Chile

[13] Stanford Univ, Dept Phys, 382 Via Pueblo Mall, Stanford, CA 94305 USA

[14] Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, POB 2450, Stanford, CA 94305 USA

[15] SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA

[16] UCL, Dept Phys & Astron, Gower St, London WC1E 6BT, England

[17] Rhodes Univ, Dept Phys & Elect, POB 94, ZA-6140 Grahamstown, South Africa

[18] Univ Portsmouth, Inst Cosmol & Gravitat, Portsmouth PO1 3FX, Hants, England

[19] Inst Astrophys Paris, CNRS, UMR 7095, F-75014 Paris, France

[20] Univ Paris 06, Inst Astrophys Paris, UMR 7095, UPMC,Sorbonne Univ, F-75014 Paris, France

[21] Lab Interinst & Astron LIneA, Rua Gal Jose Cristino 77, BR-20921400 Rio De Janeiro, Brazil

[22] Observ Nacl, Rua Gal Jose Cristino 77, BR-20921400 Rio De Janeiro, Brazil

[23] Univ Illinois, Dept Astron, 1002 W Green St, Urbana, IL 61801 USA

[24] Natl Ctr Supercomp Applicat, 1205 West Clark St, Urbana, IL 61801 USA

[25] Barcelona Inst Sci & Technol, IFAE, Campus UAB, E-08193 Bellaterra, Barcelona, Spain

[26] Univ Penn, Dept Phys & Astron, Philadelphia, PA 19104 USA

[27] CIEMAT, Madrid, Spain

[28] Steward Observ, Dept Astron, 933 North Cherry Ave, Tucson, AZ 85721 USA

[29] CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA

[30] Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA

[31] Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA

[32] Univ Autonoma Madrid, CSIC, Inst Fis Teor UAM, E-28049 Madrid, Spain

[33] IEEC, E-08193 Barcelona, Spain

[34] CSIC, ICE, Inst Space Sci, Campus UAB,Carrer Can Magrans S-N, E-08193 Barcelona, Spain

[35] Swiss Fed Inst Technol, Dept Phys, Wolfgang Pauli Str 16, CH-8093 Zurich, Switzerland

[36] Santa Cruz Inst Particle Phys, Santa Cruz, CA 95064 USA

[37] Ohio State Univ, Ctr Cosmol & Astroparticle Phys, Columbus, OH 43210 USA

[38] Ohio State Univ, Dept Phys, 174 W 18th Ave, Columbus, OH 43210 USA

[39] Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA

[40] Inst Catalana Recerca & Estudis Avancats, E-08010 Barcelona, Spain

[41] Univ Fed Rio Grande do Sul, Inst Fis, Caixa Postal 15051, BR-91501970 Porto Alegre, RS, Brazil

[42] Univ Southampton, Sch Phys & Astron, Southampton SO17 1BJ, Hants, England

[43] Brandeis Univ, Phys Dept, 415 South St, Waltham, MA 02453 USA

[44] Univ Estadual Campinas, Inst Fis Gleb Wataghin, BR-13083859 Campinas, SP, Brazil

[45] Oak Ridge Natl Lab, Comp Sci & Math Div, Oak Ridge, TN USA

来源：

ASTROPHYSICAL JOURNAL | 2018年 / 866卷 / 01期

基金：

欧洲研究理事会; 美国国家科学基金会; 澳大利亚研究理事会;

关键词：

dark matter; galaxies: dwarf; galaxies: individual (Tucana III); Local Group; stars: abundances; LONG-TERM EVOLUTION; SKY SURVEY VIEW; GLOBULAR-CLUSTER; DARK-MATTER; LEO V; SPHEROIDAL GALAXIES; BAYESIAN-INFERENCE; GALACTIC TIDES; STAR; SAGITTARIUS;

D O I：

10.3847/1538-4357/aadf91

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present a spectroscopic study of the tidal tails and core of the Milky Way satellite Tucana III, collectively referred to as the Tucana III stream, using the 2dF+AAOmega spectrograph on the Anglo-Australian Telescope and the IMACS spectrograph on the Magellan Baade Telescope. In addition to recovering the brightest nine previously known member stars in the Tucana III core, we identify 22 members in the tidal tails. We observe strong evidence for a velocity gradient of 8.0 +/- 0.4 km s(-1) deg(-1) over at least 3 degrees on the sky. Based on the continuity in velocity, we confirm that the Tucana III tails are real tidal extensions of Tucana III. The large velocity gradient of the stream implies that Tucana III is likely on a radial orbit. We successfully obtain metallicities for four members in the core and 12 members in the tails. We find that members close to the ends of the stream tend to be more metal-poor than members in the core, indicating a possible metallicity gradient between the center of the progenitor halo and its edge. The spread in metallicity suggests that the progenitor of the Tucana III stream is likely a dwarf galaxy rather than a star cluster. Furthermore, we find that with the precise photometry of the Dark Energy Survey data, there is a discernible color offset between metal-rich disk stars and metal-poor stream members. This metallicity-dependent color offers a more efficient method to recognize metal-poor targets and will increase the selection efficiency of stream members for future spectroscopic follow-up programs on stellar streams.

引用

页数：23

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