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

T. S. Li; J. D. Simon; K. Kuehn; A. B. Pace; D. Erkal; K. Bechtol; B. Yanny; A. Drlica-Wagner; J. L. Marshall; C. Lidman; E. Balbinot; D. Carollo; S. Jenkins; C. E. Martinez-Vázquez; N. Shipp; K. M. Stringer; A. K. Vivas; A. R. Walker; R. H. Wechsler; F. B. Abdalla; S. Allam; J. Annis; S. Avila; E. Bertin; D. Brooks; E. Buckley-Geer; D. L. Burke; A. Carnero Rosell; M. Carrasco Kind; J. Carretero; C. E. Cunha; C. B. D'Andrea; L. N.Da Costa; C. Davis; J. De Vicente; P. Doel; T. F. Eifler; A. E. Evrard; B. Flaugher; J. Frieman; J. Garcia-Bellido; E. Gaztanaga; D. W. Gerdes; D. Gruen; R. A. Gruendl; J. Gschwend; G. Gutierrez; W. G. Hartley; D. L. Hollowood; K. Honscheid; D. J. James; E. Krause; M. A.G. Maia; M. March; F. Menanteau; R. Miquel; A. A. Plazas; E. Sanchez; B. Santiago; V. Scarpine; R. Schindler; M. Schubnell; I. Sevilla-Noarbe; M. Smith; R. C. Smith; M. Soares-Santos; F. Sobreira; E. Suchyta; M. E.C. Swanson; G. Tarle; D. L. Tucker

doi:10.3847/1538-4357/aadf91

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

T. S. Li, J. D. Simon, K. Kuehn, A. B. Pace, D. Erkal, K. Bechtol, B. Yanny, A. Drlica-Wagner, J. L. Marshall, C. Lidman, E. Balbinot, D. Carollo, S. Jenkins, C. E. Martinez-Vázquez, N. Shipp, K. M. Stringer, A. K. Vivas, A. R. Walker, R. H. Wechsler, F. B. AbdallaS. Allam, J. Annis, S. Avila, E. Bertin, D. Brooks, E. Buckley-Geer, D. L. Burke, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, C. E. Cunha, C. B. D'Andrea, L. N.Da Costa, C. Davis, J. De Vicente, P. Doel, T. F. Eifler, A. E. Evrard, B. Flaugher, J. Frieman, J. Garcia-Bellido, E. Gaztanaga, D. W. Gerdes, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, W. G. Hartley, D. L. Hollowood, K. Honscheid, D. J. James, E. Krause, M. A.G. Maia, M. March, F. Menanteau, R. Miquel, A. A. Plazas, E. Sanchez, B. Santiago, V. Scarpine, R. Schindler, M. Schubnell, I. Sevilla-Noarbe, M. Smith, R. C. Smith, M. Soares-Santos, F. Sobreira, E. Suchyta, M. E.C. Swanson, G. Tarle, D. L. Tucker

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Abstract

We present a spectroscopic study of the tidal tails and core of the Milky Way satellite Tucana III, collectively referred to as the Tucan 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° 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.

Original language	English
Article number	22
Journal	Astrophysical Journal
Volume	866
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/aadf91
State	Published - Oct 10 2018

Funding

TSL thanks Jo Bovy and Sergey Koposov for helpful conversations. JDS acknowledges support from the National Science Foundation under grant AST-1714873. ABP acknowledges generous support from the George P. and Cynthia Woods Institute for Fundamental Physics and Astronomy at Texas A&M University. DE thanks Mark Gieles for helpful discussions. DE acknowledges financial support from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement no. 308024. EB acknowledges financial support from the European Research Council (StG-335936). The authors thank the anonymous referee for a careful reading of the manuscript and providing useful comments. Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Ministério da Ciência, Tecnologia e Inovação, the Deutsche Forschungsge-meinschaft, and the Collaborating Institutions in the Dark Energy Survey. This manuscript has been authored by the Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. Based in part on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. The DES data management system is supported by the National Science Foundation under grant Numbers AST-1138766 and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-66861, FPA2015-68048, SEV-2016-0588, SEV-2016-0597, and MDM-2015-0509, some of which include ERDF funds from the European Union. IFAE is partially funded by the CERCA program of the Generalitat de Catalunya. Research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Program (FP7/ 2007-2013), including ERC grant agreements 240672, 291329, and 306478. We acknowledge support from the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO) through project number CE110001020 and the Brazilian Instituto Nacional de Ciência e Tecnologia (INCT) e-Universe (CNPq grant 465376/2014-2).

Funders	Funder number
Brazilian Instituto Nacional de Ciência e Tecnologia
Collaborating Institutions in the Dark Energy Survey
Fermi Research Alliance, LLC	DE-AC02-07CH11359
INCT
Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University
National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign
Science and Technology Facilities Council of the United Kingdom
National Science Foundation	AST-1714873, 308024, 1138766, AST-1138766, 240672, 306478, 335936, 291329, 1714873, AST-1536171
U.S. Department of Energy
Office of Science
High Energy Physics
Ohio State University
University of Chicago
Seventh Framework Programme	FP7/ 2007-2013, FP/2007-2013
Higher Education Funding Council for England
Engineering Research Centers	StG-335936
European Commission
European Research Council
Australian Research Council	CE110001020
Deutsche Forschungsgemeinschaft
Generalitat de Catalunya
Ministerio de Economía y Competitividad	SEV-2016-0588, SEV-2016-0597, ESP2015-66861, MDM-2015-0509, FPA2015-68048, AYA2015-71825
Ministério da Ciência, Tecnologia e Inovação
Conselho Nacional de Desenvolvimento Científico e Tecnológico	465376/2014-2
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
Financiadora de Estudos e Projetos
Ministry of Education and Science of Ukraine
European Regional Development Fund

Keywords

Local Group
dark matter
galaxies: dwarf
galaxies: individual (Tucana III)
stars: abundances

Access to Document

10.3847/1538-4357/aadf91

Cite this

Li, T. S., Simon, J. D., Kuehn, K., Pace, A. B., Erkal, D., Bechtol, K., Yanny, B., Drlica-Wagner, A., Marshall, J. L., Lidman, C., Balbinot, E., Carollo, D., Jenkins, S., Martinez-Vázquez, C. E., Shipp, N., Stringer, K. M., Vivas, A. K., Walker, A. R., Wechsler, R. H., ... Tucker, D. L. (2018). The First Tidally Disrupted Ultra-faint Dwarf Galaxy? A Spectroscopic Analysis of the Tucana III Stream. Astrophysical Journal, 866(1), Article 22. https://doi.org/10.3847/1538-4357/aadf91

@article{8da011dadf5b49578ac025ac89d0d05a,

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

abstract = "We present a spectroscopic study of the tidal tails and core of the Milky Way satellite Tucana III, collectively referred to as the Tucan 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° 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.",

keywords = "Local Group, dark matter, galaxies: dwarf, galaxies: individual (Tucana III), stars: abundances",

author = "Li, {T. S.} and Simon, {J. D.} and K. Kuehn and Pace, {A. B.} and D. Erkal and K. Bechtol and B. Yanny and A. Drlica-Wagner and Marshall, {J. L.} and C. Lidman and E. Balbinot and D. Carollo and S. Jenkins and Martinez-V{\'a}zquez, {C. E.} and N. Shipp and Stringer, {K. M.} and Vivas, {A. K.} and Walker, {A. R.} and Wechsler, {R. H.} and Abdalla, {F. B.} and S. Allam and J. Annis and S. Avila and E. Bertin and D. Brooks and E. Buckley-Geer and Burke, {D. L.} and Rosell, {A. Carnero} and Kind, {M. Carrasco} and J. Carretero and Cunha, {C. E.} and D'Andrea, {C. B.} and Costa, {L. N.Da} and C. Davis and Vicente, {J. De} and P. Doel and Eifler, {T. F.} and Evrard, {A. E.} and B. Flaugher and J. Frieman and J. Garcia-Bellido and E. Gaztanaga and Gerdes, {D. W.} and D. Gruen and Gruendl, {R. A.} and J. Gschwend and G. Gutierrez and Hartley, {W. G.} and Hollowood, {D. L.} and K. Honscheid and James, {D. J.} and E. Krause and Maia, {M. A.G.} and M. March and F. Menanteau and R. Miquel and Plazas, {A. A.} and E. Sanchez and B. Santiago and V. Scarpine and R. Schindler and M. Schubnell and I. Sevilla-Noarbe and M. Smith and Smith, {R. C.} and M. Soares-Santos and F. Sobreira and E. Suchyta and Swanson, {M. E.C.} and G. Tarle and Tucker, {D. L.}",

year = "2018",

month = oct,

day = "10",

doi = "10.3847/1538-4357/aadf91",

language = "English",

volume = "866",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "1",

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Li, TS, Simon, JD, Kuehn, K, Pace, AB, Erkal, D, Bechtol, K, Yanny, B, Drlica-Wagner, A, Marshall, JL, Lidman, C, Balbinot, E, Carollo, D, Jenkins, S, Martinez-Vázquez, CE, Shipp, N, Stringer, KM, Vivas, AK, Walker, AR, Wechsler, RH, Abdalla, FB, Allam, S, Annis, J, Avila, S, Bertin, E, Brooks, D, Buckley-Geer, E, Burke, DL, Rosell, AC, Kind, MC, Carretero, J, Cunha, CE, D'Andrea, CB, Costa, LND, Davis, C, Vicente, JD, Doel, P, Eifler, TF, Evrard, AE, Flaugher, B, Frieman, J, Garcia-Bellido, J, Gaztanaga, E, Gerdes, DW, Gruen, D, Gruendl, RA, Gschwend, J, Gutierrez, G, Hartley, WG, Hollowood, DL, Honscheid, K, James, DJ, Krause, E, Maia, MAG, March, M, Menanteau, F, Miquel, R, Plazas, AA, Sanchez, E, Santiago, B, Scarpine, V, Schindler, R, Schubnell, M, Sevilla-Noarbe, I, Smith, M, Smith, RC, Soares-Santos, M, Sobreira, F, Suchyta, E, Swanson, MEC, Tarle, G & Tucker, DL 2018, 'The First Tidally Disrupted Ultra-faint Dwarf Galaxy? A Spectroscopic Analysis of the Tucana III Stream', Astrophysical Journal, vol. 866, no. 1, 22. https://doi.org/10.3847/1538-4357/aadf91

TY - JOUR

T1 - The First Tidally Disrupted Ultra-faint Dwarf Galaxy?

T2 - A Spectroscopic Analysis of the Tucana III Stream

AU - Li, T. S.

AU - Simon, J. D.

AU - Kuehn, K.

AU - Pace, A. B.

AU - Erkal, D.

AU - Bechtol, K.

AU - Yanny, B.

AU - Drlica-Wagner, A.

AU - Marshall, J. L.

AU - Lidman, C.

AU - Balbinot, E.

AU - Carollo, D.

AU - Jenkins, S.

AU - Martinez-Vázquez, C. E.

AU - Shipp, N.

AU - Stringer, K. M.

AU - Vivas, A. K.

AU - Walker, A. R.

AU - Wechsler, R. H.

AU - Abdalla, F. B.

AU - Allam, S.

AU - Annis, J.

AU - Avila, S.

AU - Bertin, E.

AU - Brooks, D.

AU - Buckley-Geer, E.

AU - Burke, D. L.

AU - Rosell, A. Carnero

AU - Kind, M. Carrasco

AU - Carretero, J.

AU - Cunha, C. E.

AU - D'Andrea, C. B.

AU - Costa, L. N.Da

AU - Davis, C.

AU - Vicente, J. De

AU - Doel, P.

AU - Eifler, T. F.

AU - Evrard, A. E.

AU - Flaugher, B.

AU - Frieman, J.

AU - Garcia-Bellido, J.

AU - Gaztanaga, E.

AU - Gerdes, D. W.

AU - Gruen, D.

AU - Gruendl, R. A.

AU - Gschwend, J.

AU - Gutierrez, G.

AU - Hartley, W. G.

AU - Hollowood, D. L.

AU - Honscheid, K.

AU - James, D. J.

AU - Krause, E.

AU - Maia, M. A.G.

AU - March, M.

AU - Menanteau, F.

AU - Miquel, R.

AU - Plazas, A. A.

AU - Sanchez, E.

AU - Santiago, B.

AU - Scarpine, V.

AU - Schindler, R.

AU - Schubnell, M.

AU - Sevilla-Noarbe, I.

AU - Smith, M.

AU - Smith, R. C.

AU - Soares-Santos, M.

AU - Sobreira, F.

AU - Suchyta, E.

AU - Swanson, M. E.C.

AU - Tarle, G.

AU - Tucker, D. L.

PY - 2018/10/10

Y1 - 2018/10/10

N2 - We present a spectroscopic study of the tidal tails and core of the Milky Way satellite Tucana III, collectively referred to as the Tucan 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° 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.

AB - We present a spectroscopic study of the tidal tails and core of the Milky Way satellite Tucana III, collectively referred to as the Tucan 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° 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.

KW - Local Group

KW - dark matter

KW - galaxies: dwarf

KW - galaxies: individual (Tucana III)

KW - stars: abundances

UR - http://www.scopus.com/inward/record.url?scp=85055315576&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aadf91

DO - 10.3847/1538-4357/aadf91

M3 - Article

AN - SCOPUS:85055315576

SN - 0004-637X

VL - 866

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 22

ER -