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Agradecimentos: 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. Based on data obtained at Siding Spring Observatory via program A/2016A/26. We acknowledge the traditional owners of the land on which the AAT stands, the Gamilaraay people, and pay our respects to elders past and present. This research has made use of NASA’s Astrophysics Data System Bibliographic Services. This paper has gone through internal review by the DES collaboration. 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 Forschungsgemeinschaft, and the Collaborating Institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas-Madrid, the University of Chicago, University College London, the DESBrazil Consortium, the University of Edinburgh, the Eidgenössische Technische Hochschule (ETH) Zürich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ciències de l’Espai (IEEC/CSIC), the Institut de Física d’Altes Energies, Lawrence Berkeley National Laboratory, Ludwig-Maximilians Universität München and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, The Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, Texas A&M University, and the OzDES Membership Consortium. 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 Astro-physics (CAASTRO) through project number CE110001020 and the Brazilian Instituto Nacional de Ciencia e Tecnologia (INCT) e-Universe (CNPq grant 465376/2014-2). 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 Abstract: 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 FINANCIADORA DE ESTUDOS E PROJETOS - FINEP FUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIRO - FAPERJ CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ MINISTÉRIO DA CIÊNCIA, TECNOLOGIA, INOVAÇÕES E COMUNICAÇÕES - MCTIC Aberto

Agradecimentos: N.S. acknowledges support by NASA ATP grant NNH12ZDA001N and NSF grant AST-1412107 and thanks the LSSTC Data Science Fellowship Program; her time as a Fellow has benefited this work. E.B. acknowledges financial support from the European Research Council (ERC-StG-335936). 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, Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico and the Ministerio da Ciencia, Tecnologia e Inovacao, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenossische Technische Hochschule (ETH) Zurich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ciencies de l'Espai (IEEC/CSIC), the Institut de Fisica d'Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universitat Munchen and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, The Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, Texas A&M University, and the OzDES Membership Consortium. 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 agrément with the National Science Foundation. The DES data management system is supported by the National Science Foundation under grant nos. AST-1138766 and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-88861, FPA2015-68048, SEV-2012-0234, 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 no. CE110001020. This manuscript has been authored by 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 Abstract: We perform a search for stellar streams around the Milky Way using the first 3 yr of multiband optical imaging data from the Dark Energy Survey (DES). We use DES data covering similar to 5000 deg(2) to a depth of g gt; 23.5 with a relative photometric calibration uncertainty of

En diferentes estudios sobre las galaxias enanas esferoidales (dSph) de la Vía Láctea se arma que estos sistemas podrían estar dominados por materia oscura debido a los altos valores registrados en la razón masa-luminosidad M/L observacional. Sin embargo, aún no es claro si las razones M/L de las dSph inferidas de las observaciones son reales o si por el contrario podrían ser producto de suponer erróneamente que las dSph de la Vía Láctea son sistemas en equilibrio virial. En el último caso, las galaxias dSph podrían carecer de materia oscura. En este trabajo se presenta un estudio de la evolución de diferentes posibles progenitores sin materia oscura de la galaxia enana esferoidal Carina, una de las galaxias satélites de la Vía Láctea, mediante simulaciones numéricas Newtonianas de N-Cuerpos. En el estudio se realizaron varias simulaciones caracterizadas por satélites que inicialmente se modelan como esferas de Plummer con masas entre 106 M¤ y 108 M¤ , radios de Plummer entre 0.2 y 0.8 kpc y con 105 partículas para el posible progenitor de Carina. Las simulaciones se realizaron con el programa Gadget2. Se analizó la evolución, la posible deformación de los objetos iniciales debido a los pasos perigalácticos alrededor de la Vía Láctea y se compararon las características de los objetos remanentes en las simulaciones con las correspondientes características observadas para la dSph Carina. En total se realizaron catorce simulaciones Newtonianas de N-cuerpos, para la distancia apocéntrica de 100 kpc, con el fin de buscar los posibles progenitores dela galaxia de estudio (Carina). Cuatro simulaciones correspondieron a una masa inicial de 106 M¤ y un rango de radio de Plummer entre 0.2-0.8 kpc; cinco correspondieron a una masa inicial de 107 M¤ y cuyo radio de Plummer fue modificado para cada una entre 0.2-0.6 kpc; cinco correspondieron a una masa inicial de 108 M¤ y cuyo radio de Plummer fue modificado para cada una entre 0.4-0.8 kpc. De acuerdo con el análisis de las simulaciones realizadas, no fue posible reproducir completamente las propiedades observacionales de la galaxia enana esferoidal Carina, y por consiguiente no se pudo determinar un posible progenitor carente de materia oscura para la misma; sin embargo, para la masa 107 M¤ y los radios de Plummer 0.5 y 0.6 kpc, tres de las cinco variables σ0, Rgc, R1/2 estudiadas tomaron valores observacionales de la galaxia Carina (en el intervalo de tiempo IV (6-8 Gyr)y (5.7-6.5 Gyr) respectivamente) y aunque no todas las variables coincidieron con los valores observacionales, se puede armar que esta masa puede ser la base para posteriores trabajos. In dierent studies of dwarf spheroidal galaxies (dSph) of the Milky Way, it is claimed that these systems could be dominated by dark matter due to the high values recorded in the observational mass-luminosity ratio M/L. However, it is still unclear whether these values inferred from the observations are real or whether on the contrary could be caused by wrongly assuming that the Milky Way dSph are systemsin virial equilibrium. In the latter case, the dSph galaxies may lack dark matter. This paper presents a study of the evolution of dierent possible progenitors occurs without dark matter in dwarf spheroidal galaxy Carina, one of the satellite galaxies of the Milky Way, using Newtonian N-Body numerical simulations . Several simulations characterized by satellites initially modeled as Plummer spheres with masses between 106 M¤ and 108 M¤, Plummer's radio between 0.2 and 0.8 kpc and 105 implemented with Gadget2 program. Evolution is analyzed, possible deformation of initial objects because perigalactics steps around the Milky Way and features of the remaining objects in the simulations were compared with the corresponding observed characteristics for dSph Carina. In conclusion, although not a parent for the dwarf galaxy Carina was obtained, it was possible to find kinematic properties, mass: 107 M¤, Plummers radio 0.5-0.6 kpc and, da = 100kpc, which in most simulations, correspond to a possible parent. Maestría

En la actualidad dentro del área de la astrofísica se presentan un sinnúmero de problemas sin resolver, entre ellos el problema del origen de las galaxias satélite de la VL. Estas galaxias se caracterizan por ser de tipo enana esferoidal. La mayoría de estas se encuentran distribuidas en una estructura tipo disco que se encuentra dispuesta de casi forma perpendicular al plano de la galaxia, esta estructura es conocida con el nombre de disco de satélites (DoS) o Vast Polar Structure Of Satellite Galaxies (VPOS). Hasta el momento no se ha podido encontrar un modelo que dé cuenta de la cantidad y de la distribución espacial de estas galaxias. Sin embargo se han presentado varias propuestas de solución para el caso de la VL, una de las cuales propone que estas tuvieron origen en la colisión de dos galaxias de disco hace miles de millones de años. En este trabajo se llevaron a cabo simulaciones numéricas de N-cuerpos con el software Gadget2 para colisiones entre dos galaxias de disco que pudieron dar origen al disco de satélites de la VL. Se puede decir que bajo las condiciones iniciales planteadas para estas simulaciones no es posible generar las características dinámicas y espaciales de lo que se denomina el disco de galaxias satélite la VL (DoS), sin embargo, esto no descarta por completo el modelo propuesto para este estudio, ya que si bien no refleja los resultados esperados, se pueden proponer trabajos futuros para realizar simulaciones y modificar los parámetros de impacto y las relaciones de masa y así poder enmarcar las condiciones físicas bajo las cuales sería posible este evento. Los resultados de este trabajo permiten acotar aún más el espacio de condiciones iniciales orbitales y de masa de eventuales progenitores del DoS de la VL. Abstract At present within the area of astrophysics there are a number of unresolved problems, including the problem of the origin of the satellite galaxies of the Milky Way. These galaxies are characterized by dwarf spheroidal galaxies type. Most of them are distributed in a disk-like structure which is arranged almost perpendicular to the plane of the galaxy, this structure is known as satellite disk (DoS) or Polar Structure Of Vast Satellite Galaxies (VPOS). So far there is not a model that fully reproduces the amount and spatial distribution of these galaxies. However there have been several proposed for the solutions, one of which suggests that these originated in the collision of two disk galaxies billions of years ago. In this work we have performed N-bodies numerical simulations of with Gadget2 of the collision between two disk galaxies that could give rise to disc of VL satellites. It can be said that under the initial conditions set for these simulations is not possible to generate dynamic and spatial characteristics of what is called the satellite the disc of Milky Way (DoS) galaxies, however, this does not preclude in any way the model proposed for this study because although it does not reflect the expected results can be proposed for future work simulations and modify the parameters of impact and the mass ratios to frame the physical conditions under which this event possible. The results of this work allow limiting further orbital space initial conditions and eventual mass progenitors of DoS VL. Maestría

Se estudia un posible escenario de formación para el disco de satélites de la vía láctea a partir de la caída de una asociación de enanas perteneciente al grupo local que por sus características dinámicas, estructurales y observacionales podría ser considerada como un posible progenitor de algunas de las galaxias del sistema de satélites de la vía láctea. La evolución dinámica del posible progenitor se evalúa a través de los tiempos de fricción dinámica asociados a las agrupaciones del filamento 14 y a partir de estos se verifica la plausibilidad de la asociación como progenitor del sistema de satélites. Abstract. We study a Disc of Satellites formation scenario through the interaction of an association of dwarf galaxies belonging to the local group that can be considered due to its dynamical, structural and observational properties as a progenitor of the milky way galaxy satellites. The dynamic evolution associated to this progenitor is evaluated using the dynamical friction time for the associations of the filament 14 and from this results can be verified the physical status of this association as a progenitor of the Milky Way satellite system. Maestría

Las galaxias satélite de la Vía Láctea son de especial importancia para el estudio de la formación y evolución de galaxias, así como para el estudio de la materia oscura. En este artículo de revisión se presentan algunas propiedades estructurales del Grupo Local y de las galaxias enanas esferoidales que componen este sistema, con especial énfasis en las galaxias satélite de la Vía Láctea y su distribución espacial en el disco de satélites. Adicionalmente se presentan los estudios recientes más relevantes relacionados con el problema de la formación del disco de satélites de la Vía Láctea. The satellite galaxies of the Milky Way are very important both for the studies of the formation and evolution of galaxies and for the research on the dark matter problem. In the present review paper some structural properties of the Local Group, as well as of the dwarf spheroidal galaxies that compose this astrophysical system are presented. Special emphasis is paid to the satellite galaxies of the Milky Way and their spatial distribution on the disk of satellites (DoS). Furthermore, the more relevant recent studies related to the formation of the disk of satellites of the Milky Way are mentioned.