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12 results on '"E. Balbinot"'

1. Modelling the Milky Way – I. Method and first results fitting the thick disc and halo with DES-Y3 data

Author

Erin Sheldon, M. E. C. Swanson, Alex Drlica-Wagner, R. L. C. Ogando, Enrique Gaztanaga, Andrew B. Pace, L. Girardi, M. Carrasco Kind, David J. Brooks, E. Balbinot, G. Tarle, G. Gutierrez, K. Bechtol, Adriano Pieres, Jennifer L. Marshall, B. Flaugher, Vinu Vikram, Marcelle Soares-Santos, E. Suchyta, A. Carnero Rosell, Juan Garcia-Bellido, E. Bertin, A. A. Plazas, Tenglin Li, Santiago Avila, Daniel Thomas, I. Sevilla-Noarbe, M. dal Ponte, K. Honscheid, J. Gschwend, N. Kuropatkin, Flavia Sobreira, Ramon Miquel, L. N. da Costa, Martin Groenewegen, S. Desai, H. T. Diehl, D. L. Burke, David J. James, Basilio X. Santiago, A. R. Walker, Pablo Fosalba, E. J. Sanchez, Robert A. Gruendl, J. De Vicente, Adam Amara, Kyler Kuehn, Tim Eifler, M. Smith, Daniel Gruen, D. W. Gerdes, D. L. Hollowood, S. Serrano, J. Carretero, Josh Frieman, M. A. G. Maia, Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), DES, Astronomy, Department of Energy (US), National Science Foundation (US), Ministerio de Ciencia, Innovación y Universidades (España), Science and Technology Facilities Council (UK), University of Illinois, Kavli Institute for Theoretical Physics, University of Chicago, The Ohio State University, Texas A&M University, Financiadora de Estudos e Projetos (Brasil), Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil), Ministério da Ciência, Tecnologia e Inovação (Brasil), and German Research Foundation

Subjects
astro-ph.SR, astro-ph.GA, Milky Way, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Star count, 01 natural sciences, 7. Clean energy, Galactic halo, 0103 physical sciences, halo [Galaxy], stellar content [Galaxy], Astrophysics::Solar and Stellar Astrophysics, Large Magellanic Cloud, Galaxy: structure, 010303 astronomy & astrophysics, Stellar density, Solar and Stellar Astrophysics (astro-ph.SR), STFC, Astrophysics::Galaxy Astrophysics, Dwarf galaxy, Physics, Galaxy: stellar content, 010308 nuclear & particles physics, RCUK, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Galaxy: halo, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Globular cluster, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], structure [Galaxy]
Abstract

Full author list: A Pieres, L Girardi, E Balbinot, B Santiago, L N da Costa, A Carnero Rosell, A B Pace, K Bechtol, M A T Groenewegen, A Drlica-Wagner, T S Li, M A G Maia, R L C Ogando, M dal Ponte, H T Diehl, A Amara, S Avila, E Bertin, D Brooks, D L Burke, M Carrasco Kind, J Carretero, J De Vicente, S Desai, T F Eifler, B Flaugher, P Fosalba, J Frieman, J García-Bellido, E Gaztanaga, D W Gerdes, D Gruen, R A Gruendl, J Gschwend, G Gutierrez, D L Hollowood, K Honscheid, D J James, K Kuehn, N Kuropatkin, J L Marshall, R Miquel, A A Plazas, E Sanchez, S Serrano, I Sevilla-Noarbe, E Sheldon, M Smith, M Soares-Santos, F Sobreira, E Suchyta, M E C Swanson, G Tarle, D Thomas, V Vikram, A R Walker, We present a technique to fit the stellar components of the Galaxy by comparing Hess Diagrams (HDs) generated from TRILEGAL models to real data. We apply this technique, which we call MWFITTING, to photometric data from the first 3 yr of the Dark Energy Survey (DES). After removing regions containing known resolved stellar systems such as globular clusters, dwarf galaxies, nearby galaxies, the Large Magellanic Cloud, and the Sagittarius Stream, our main sample spans a total area of ~2300 deg2. We further explore a smaller subset (~1300 deg2) that excludes all regions with known stellar streams and stellar overdensities. Validation tests on synthetic data possessing similar properties to the DES data show that the method is able to recover input parameters with a precision better than 3 per cent. We fit the DES data with an exponential thick disc model and an oblate double power-law halo model. We find that the best-fitting thick disc model has radial and vertical scale heights of 2.67 ± 0.09 kpc and 925 ± 40 pc, respectively. The stellar halo is fit with a broken power-law density profile with an oblateness of 0.75 ± 0.01, an inner index of 1.82 ± 0.08, an outer index of 4.14 ± 0.05, and a break at 18.52 ± 0.27 kpc from the Galactic centre. Several previously discovered stellar overdensities are recovered in the residual stellar density map, showing the reliability of MWFITTING in determining the Galactic components. Simulations made with the best-fitting parameters are a promising way to predict Milky Way star counts for surveys such as the LSST and Euclid., The DESDM is supported by the National Science Foundation under grants 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 Ci?ncia e Tecnologia (INCT) do e-Universe (CNPq grant 465376/2014-2). 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 non-exclusive, 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. 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 Centre for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Centre for Cosmology and AstroParticle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundac¸ão Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Ministério da Ciência, Tecnologia e Inovac¸ão, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the DES.

Published
2020
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2. Linking nearby stellar streams to more distant halo overdensities

Author

A. Helmi, E. Balbinot, and Astronomy

Subjects
Physics, Milky Way, media_common.quotation_subject, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Debris, Accretion (astrophysics), Galaxy, Galaxy: halo, Orbit, Stars, Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Solar and Stellar Astrophysics, Halo, Astrophysics::Earth and Planetary Astrophysics, Galaxy: kinematics and dynamics, Astrophysics::Galaxy Astrophysics, media_common
Abstract

It has been recently shown that the halo near the Sun contains several kinematic substructures associated to past accretion events. For the more distant halo, there is evidence of large-scale density variations -- in the form of stellar clouds or overdensities. We study the link between the local halo kinematic groups and three of these stellar clouds: the Hercules-Aquila cloud, the Virgo Overdensity, and the Eridanus-Phoenix overdensity. We perform orbital integrations in a standard Milky Way potential of a local halo sample extracted from Gaia eDR3, with the goal of predicting the location of the merger debris elsewhere in the Galaxy. We specifically focus on the regions occupied by the three stellar clouds and compare their kinematic and distance distributions with those predicted from the orbits of the nearby debris. We find that the local halo substructures have families of orbits that tend to pile up in the regions where the stellar clouds have been found. The distances and velocities of the cloud's member stars are in good agreement with those predicted from the orbit integrations, particularly for Gaia-Enceladus stars. This is the dominant contributor of all three overdensities, with a minor part stemming from the Helmi streams and to an even smaller extent from Sequoia. The orbital integrations predict no asymmetries in the sky distribution of halo stars, and they pinpoint where additional debris associated with the local halo substructures may be located., Comment: 6 pages, 6 figures. Accepted to A&A

Published
2021
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3. The southern stellar stream spectroscopic survey (S5)

Author

Lara R. Cullinane, A. K. Vivas, E. Balbinot, Vasily Belokurov, Daniel B. Zucker, Sergey E. Koposov, Jeffrey D. Simpson, Sanjib Sharma, Alasdair Mackey, Denis Erkal, G. M. De Silva, Douglas L. Tucker, Risa H. Wechsler, J. D. Simon, Keith Bechtol, Kyler Kuehn, Alexander P. Ji, Geraint F. Lewis, Alex Drlica-Wagner, Brian Yanny, Marla Geha, Joss Bland-Hawthorn, Andrew B. Pace, S. Allam, Nora Shipp, G. S. Da Costa, Tenglin Li, Andrew R. Casey, Jeremy Mould, Zhen Wan, Yao-Yuan Mao, Sarah L. Martell, and Astronomy

Subjects
TIDAL STREAMS, Milky Way, media_common.quotation_subject, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, MASS, 01 natural sciences, globular clusters: general, Photometry (optics), Galactic halo, DARK HALO, galaxy: halo, 0103 physical sciences, SPECTROGRAPH, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Dwarf galaxy, media_common, Physics, RADIAL-VELOCITIES, 010308 nuclear & particles physics, Astronomy, Astronomy and Astrophysics, galaxies: dwarf, Astrophysics - Astrophysics of Galaxies, GIANT STARS, Galaxy, EVOLUTION, GALAXY, Dark matter halo, Space and Planetary Science, Sky, Globular cluster, Astrophysics of Galaxies (astro-ph.GA), galaxy: kinematics and dynamics, DIGITAL SKY SURVEY, MILKY-WAY, Astrophysics::Earth and Planetary Astrophysics
Abstract

We introduce the Southern Stellar Stream Spectroscopy Survey (${S}^5$), an on-going program to map the kinematics and chemistry of stellar streams in the Southern Hemisphere. The initial focus of ${S}^5$ has been spectroscopic observations of recently identified streams within the footprint of the Dark Energy Survey (DES), with the eventual goal of surveying streams across the entire southern sky. Stellar streams are composed of material that has been tidally striped from dwarf galaxies and globular clusters and hence are excellent dynamical probes of the gravitational potential of the Milky Way, as well as providing a detailed snapshot of its accretion history. Observing with the 3.9-m Anglo-Australian Telescope's 2-degree-Field fibre positioner and AAOmega spectrograph, and combining the precise photometry of DES DR1 with the superb proper motions from $Gaia$ DR2, allows us to conduct an efficient spectroscopic survey to map these stellar streams. So far ${S}^5$ has mapped 9 DES streams and 3 streams outside of DES; the former are the first spectroscopic observations of these recently discovered streams. In addition to the stream survey, we use spare fibres to undertake a Milky Way halo survey and a low-redshift galaxy survey. This paper presents an overview of the ${S}^5$ program, describing the scientific motivation for the survey, target selection, observation strategy, data reduction and survey validation. Finally, we describe early science results on stellar streams and Milky Way halo stars drawn from the survey. Updates on ${S}^5$, including future public data release, can be found at \url{http://s5collab.github.io}., Comment: 25 pages, 14 figures (1 in appendix), 3 tables (1 in appendix). Published on MNRAS. See also paper from Shipp et al. 2019, which measures the proper motion of the DES streams

Published
2019
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4. The Galactic Anticentre

Author

Vincenzo Ripepi, A. de Torres, Annie C. Robin, Mariateresa Crosta, C. Diener, L. Noval, Daniel Michalik, P. J. Richards, L. Karbevska, K. Kruszyńska, E. Fraile, André Moitinho, Michał Pawlak, P. Panuzzo, M. Riello, Benoit Carry, A. Yoldas, Harry Enke, N. Tonello, P. Gavras, M. Vaillant, Rosanna Sordo, E. del Pozo, Lorenzo Rimoldini, M. Bernet, G. Orrù, W. van Reeven, J. M. Martín-Fleitas, S. Diakite, P. Burgess, P. Osborne, Derek W. Morris, M. I. Carnerero, Amina Helmi, Mike Smith, Iain A. Steele, Alessandro Sozzetti, M. Kontizas, A. Sagristà Sellés, Roberto Molinaro, B. Holl, D. Baines, D. Molina, J. Fernández-Hernández, S. Marinoni, Michele Bellazzini, Maria Süveges, Teresa Antoja, D. Barbato, Uwe Lammers, Isabella Pagano, Davide Massari, G. Plum, P. Ramos, G. Jevardat de Fombelle, M. Biermann, C. Crowley, Mathias Schultheis, D. W. Evans, P. A. Palicio, Paolo Montegriffo, Ramachrisna Teixeira, R. Blomme, Elmé Breedt, T. A. Lister, F. A. Jansen, Ruth Carballo, Marcella Marconi, A. Abreu Aramburu, J. M. Carrasco, F. Royer, S. Accart, A. Burlacu, S. Regibo, Andrej Prsa, M. Sarasso, Nicolas Rambaux, A. F. Mulone, Ana Ulla, Eric Gosset, Alessandra Mastrobuono-Battisti, George M. Seabroke, H. E. Delgado, Federico Marocco, C. Nicolas, T. Lebzelter, Nami Mowlavi, C. Barache, Nicoletta Sanna, G. Gracia-Abril, R. Santoveña, R. Haigron, N. Unger, Silvio Leccia, A. Jean-Antoine Piccolo, A. F. Lanza, Alberto Vecchiato, Thomas Wevers, F. Figueras, G. Busso, C. Fabre, P. Di Matteo, F. Riclet, F. Solitro, Eric Slezak, N. Samaras, João Alves, Emese Plachy, Timo Prusti, F. van Leeuwen, J. Osinde, O. Marchal, M. Ajaj, C. Ducourant, Tatiana Muraveva, Shay Zucker, H. Steidelmüller, Alberto Riva, D. Semeux, N. Cheek, Laurent Galluccio, Martin A. Barstow, Alex Bombrun, S. Liao, M. van Leeuwen, R. E. de Souza, P. de Laverny, T. Roegiers, Paul J. McMillan, G. Holland, Alexey Mints, G. Giuffrida, L. M. Sarro, Juan Zorec, G. Sadowski, P. Yvard, Carme Jordi, J. L. Halbwachs, Laurent Chemin, Ludovic Delchambre, M. Garcia-Reinaldos, Ugo Becciani, Diego Bossini, Ángel Gómez, Sergi Blanco-Cuaresma, Rossella Cancelliere, C. Fabricius, J. De Ridder, L. Eyer, L. Pulone, Simon Hodgkin, Ennio Poretti, F. De Angeli, M. Haywood, E. Anglada Varela, Antonella Vallenari, F. X. Pineau, D. Garabato, A. Guerrier, H. E. P. Lindstrøm, Thomas Hilger, I. Bellas-Velidis, Frédéric Arenou, Paolo Giacobbe, Ilaria Musella, Tristan Cantat-Gaudin, L. Palaversa, Pedro García-Lario, David Hobbs, C. Turon, E. Balbinot, P. de Teodoro, Sébastien Lambert, D. Katz, Angela Bragaglia, Anthony G. A. Brown, Paolo Tanga, P. Castro Sampol, J. C. Segovia, Alejandra Recio-Blanco, Yves Fremat, Jon Marchant, Jose M Hernandez, S. Ragaini, Sofia Randich, P. Re Fiorentin, J. F. Le Campion, Gisella Clementini, M. Segol, P. David, R. Drimmel, F. Crifo, J. Guiraud, M. David, R. L. Smart, M. Fabrizio, I. Gonzalez-Santamaria, D. Eappachen, M. G. Lattanzi, Miguel García-Torres, Andreas Korn, S. Voutsinas, László Molnár, Simchon Faigler, A. Mora, Nicholas Rowell, Antti Penttilä, R. Geyer, Sanjeev Khanna, Aldo Dell'Oro, H. E. Huckle, C. Dolding, N. Leclerc, Monica Rainer, R. Mor, J. Bakker, Maroussia Roelens, Douglas J. Marshall, A. G. Butkevich, Nigel Hambly, A. Masip, Laia Casamiquela, R. Messineo, Martin Altmann, A. M. Piersimoni, Alessandro Spagna, Gerry Gilmore, Stefano Bertone, Patrick Charlot, O. Vanel, Daniel Hestroffer, Marco Castellani, Sebastian L. Hidalgo, W. Roux, Łukasz Wyrzykowski, Krzysztof A. Rybicki, M. M. S. Marcos Santos, Raphael Guerra, Alberto Cellino, E. Poggio, Gérard Jasniewicz, J. J. González-Vidal, S. Cowell, Peter G. Jonker, C. M. Raiteri, S. Bartolomé, J. Álvarez Cid-Fuentes, Elisabetta Caffau, J. J. Aguado, N. R. Millar, Ulrike Heiter, Federica Spoto, Felix Franke, A. Baudesson-Stella, M. Barros, Tsevi Mazeh, A. Panahi, E. Brugaletta, R. Buzzi, Elena Pancino, G. Altavilla, E. Racero, Enrique Solano, Mikael Granvik, Minia Manteiga, C. Robin, Tomaz Zwitter, Deborah Busonero, Alberto Krone-Martins, Marc Audard, Kevin Benson, Christos Siopis, L. Balaguer-Núñez, C. A. L. Bailer-Jones, E. Poujoulet, O. L. Creevey, E. Szegedi-Elek, C. Fouron, Michael Davidson, E. Licata, Despina Hatzidimitriou, Mark Cropper, Z. Kostrzewa-Rutkowska, S. Managau, A. Dapergolas, Sergio Messina, Laszlo Szabados, H. I. Siddiqui, W. Löffler, Mario Gai, J.-B. Delisle, Leanne P. Guy, S. G. Baker, W. J. Cooper, Alfred Castro-Ginard, Conny Aerts, A. Lorca, Xavier Luri, Damien Ségransan, Grigori Fedorets, A. Garofalo, J. Juaristi Campillo, F. De Luise, F. Pailler, F. Taris, L. Bramante, Thierry Morel, T. Cornez, L. Martin Polo, M. Ramos-Lerate, Jordi Portell, E. Salguero, Sergei A. Klioner, K. Janßen, Ulrich Bastian, Stefan Jordan, P. Esquej, A. C. Lanzafame, Beatrice Bucciarelli, C. Panem, Y. Lebreton, Carlos Dafonte, S. Girona, D. Munoz, Dimitri Pourbaix, William Thuillot, J. H. J. de Bruijne, N. Brouillet, L. Chaoul, F. Torra, Alex Lobel, J.-L. Bassilana, Francesca Fragkoudi, M. Romero-Gómez, C. A. Stephenson, T. Pauwels, Eva Sciacca, Alessandro Bressan, Morgan Fouesneau, E. Livanou, E. Gerlach, X. Peñalosa Esteller, Roberto Morbidelli, L. Rohrbasser, Johannes Sahlmann, Elisa Distefano, P. Sartoretti, Karri Muinonen, Zoltan Balog, Y. Viala, J. Torra, H. Zhao, L. Siltala, G. Tauran, D. Souami, P. Madrero Pardo, David Teyssier, Jesus Salgado, J. Souchay, C. P. Murphy, Maria-Rosa L. Cioni, N. A. Walton, S. Bouquillon, Andrea Chiavassa, Agnes Fienga, Giovanni Comoretto, F. Julbe, A. Hutton, Yassine Damerdji, Richard I. Anderson, Pierre Fernique, Céline Reylé, M. Hauser, E. Utrilla, Pierre Kervella, C. Zurbach, Robert G. Mann, Ummi Abbas, Hector Canovas, D. L. Harrison, Y. Lasne, Mark Taylor, Y. Le Fustec, E. F. del Peloso, N. Bauchet, E. van Dillen, Jan Rybizki, N. Hładczuk, T. Boch, J. González-Núñez, Carine Babusiaux, C. Pagani, Krzysztof Nienartowicz, Eduard Masana, G. Kordopatis, N. Robichon, Luciana Bianchi, R. Gutiérrez-Sánchez, Arnaud Siebert, A. Kochoska, T. Carlucci, Jérôme Berthier, J. Castañeda, D. Vicente, R. De March, A. Garcia-Gutierrez, M. Weiler, F. Thévenin, Lennart Lindegren, Isabelle Lecoeur-Taïbi, Guy Rixon, Francois Mignard, P. M. Marrese, M. A. Álvarez, Caroline Soubiran, Rene Andrae, C. Ordénovic, A. Delgado, V. Sanchez Gimenez, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), Universidad de Barcelona, Xunta de Galicia, European Commission, Centros de Excelencia Severo Ochoa, BARCELONA SUPERCOMPUTING CENTER (BSC), SEV2015-0493, Krone Martins, A. [0000-0002-2308-6623], McMillan, P. [0000-0002-8861-2620], Carrasco Martínez, J. P. [0000-0002-3029-5853], Sozzetti, A. [0000-0002-7504-365X], Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MINECO/ICTI2013-2016/MDM-2014-0369, Centrode Excelencia Científica Instituto de Ciencias del Cosmos Universidad de Barcelona, MINECO/ICTI2013-2016/SEV2015-0493, Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), National Natural Science Foundation of China (NSFC), Estonian Ministry of Education and Research, Centre National D'Etudes Spatiales (CNES), Agence Nationale de la Recherche (ANR), Centre National de la Recherche Scientifique (CNRS), European Commission (EC), European Research Council (ERC), Institut des Sciences de l'Univers (INSU), Institut National Polytechnique (INP), Institut National de Physique nucleaire et de Physique des Particules (IN2P3), Deutsches Zentrum für Luft- und Raumfahrt (DLR), Hungarian Academy of Sciences, Hungarian National Research, Development, and Innovation Office (NKFIH), Science Foundation Ireland (SFI), Israel Science Foundation (ISF), Agenzia Spaziale Italiana (ASI), Italian Istituto Nazionale di Astrofisica (INAF), Netherlands Organisation for Scientific Research (NWO), Polish National Science Centre, Ministry of Science and Higher Education (MNiSW), Fundacao para a Ciencia e a Tecnologia (FCT), Slovenian Research Agency, Agencia Estatal de Investigación (AEI), Generalitat de Catalunya, United Kingdom Science and Technology Facilities Council (STFC), United Kingdom Space Agency (UKSA), Gaia Collaboration, Universidad de Cantabria, Astronomy, Kapteyn Astronomical Institute, Institut de Ciencies del Cosmos (ICCUB), Universitat de Barcelona (UB), Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), M2A 2021, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Planetary-system research, Department of Physics, Particle Physics and Astrophysics, Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (... - 2019) (UNS), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
trigonometric parallaxes, SOLAR NEIGHBORHOOD, Astronomy, SAGITTARIUS DWARF GALAXY, Astrophysics, 01 natural sciences, sagittarius dwarf galaxy, 010303 astronomy & astrophysics, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], solar neighborhood, Astrophysics::Instrumentation and Methods for Astrophysics, Astrometry, Gelexy: kinematics and dynamics, Kinematics and Dynamics, Open clusters and asssociations: individual: Berkeley 29, sky survey, Disk, Physical Sciences, kinematics and dynamics [Gelexy], old open clusters, MILKY-WAY, Astrophysics::Earth and Planetary Astrophysics, open clusters and associations: individual: Berkeley 29, Galaxy: kinematics and dynamics, disk [Galaxy], individual: Berkeley 29 [open clusters and associations], Astrometria, Berkeley 29, EXPLORING HALO SUBSTRUCTURE, LOCAL KINEMATICS, Milky Way, FOS: Physical sciences, Open Clusters and Associations, Individual, exploring halo substructure, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, Computer Science::Digital Libraries, stellar structure, Galaxy: disk, Open clusters and associations: individual: Saurer 1, Galactic halo, Halo, Settore FIS/05 - Astronomia e Astrofisica, individual: Berkeley 29 [Open clusters and asssociations], 0103 physical sciences, distances [stars], halo [Galaxy], Disc, Stars: distances, milky-way, Saurer 1, Astrophysics::Galaxy Astrophysics, canis-major, Science & Technology, 010308 nuclear & particles physics, TRIGONOMETRIC PARALLAXES, Galaxy: halo, stars: distances, open clusters and associations: individual: Saurer 1, Astrophysics - Astrophysics of Galaxies, Astronomy and Astrophysics, Galactic plane, kinematics and dynamics [Galaxy], 115 Astronomy, Space science, CANIS-MAJOR, Stars, Galaxy, Physics::History of Physics, Estels, individual: Saurer 1 [open clusters and associations], Distances, local kinematics, OLD OPEN CLUSTERS, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), SKY SURVEY, Open cluster, STELLAR STRUCTURE
Abstract

Aims. We aim to demonstrate the scientific potential of the Gaia Early Data Release 3 (EDR3) for the study of different aspects of the Milky Way structure and evolution and we provide, at the same time, a description of several practical aspects of the data and examples of their usage., Methods. We used astrometric positions, proper motions, parallaxes, and photometry from EDR3 to select different populations and components and to calculate the distances and velocities in the direction of the anticentre. In this direction, the Gaia astrometric data alone enable the calculation of the vertical and azimuthal velocities; also, the extinction is relatively low compared to other directions in the Galactic plane. We then explore the disturbances of the current disc, the spatial and kinematical distributions of early accreted versus in situ stars, the structures in the outer parts of the disc, and the orbits of open clusters Berkeley 29 and Saurer 1., Results. With the improved astrometry and photometry of EDR3, we find that: (i) the dynamics of the Galactic disc are very complex with oscillations in the median rotation and vertical velocities as a function of radius, vertical asymmetries, and new correlations, including a bimodality with disc stars with large angular momentum moving vertically upwards from below the plane, and disc stars with slightly lower angular momentum moving preferentially downwards; (ii) we resolve the kinematic substructure (diagonal ridges) in the outer parts of the disc for the first time; (iii) the red sequence that has been associated with the proto-Galactic disc that was present at the time of the merger with Gaia-Enceladus-Sausage is currently radially concentrated up to around 14 kpc, while the blue sequence that has been associated with debris of the satellite extends beyond that; (iv) there are density structures in the outer disc, both above and below the plane, most probably related to Monoceros, the Anticentre Stream, and TriAnd, for which the Gaia data allow an exhaustive selection of candidate member stars and dynamical study; and (v) the open clusters Berkeley 29 and Saurer 1, despite being located at large distances from the Galactic centre, are on nearly circular disc-like orbits., Conclusions. Even with our simple preliminary exploration of the Gaia EDR3, we demonstrate how, once again, these data from the European Space Agency are crucial for our understanding of the different pieces of our Galaxy and their connection to its global structure and history.

Published
2021
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5. Variable stars in Local Group Galaxies -- V. The fast and early evolution of the low-mass Eridanus II dSph galaxy

Author

Marcella Marconi, A. R. Walker, E. Balbinot, Peter B. Stetson, S. Cassisi, Matteo Monelli, L. Cicuendez, Annalisa Calamida, C. E. Martínez-Vázquez, Stefania Salvadori, Giuseppina Battaglia, Massimo Dall'Ora, S. Taibi, Carme Gallart, Daniela Carollo, P. Martín-Ravelo, Edouard J. Bernard, Giuseppe Bono, A. K. Vivas, Alfredo Zenteno, Giuliana Fiorentino, and Astronomy

Subjects
Cepheid variable, Milky Way, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, RR Lyrae variable, Galaxies: Evolution, Astrophysics::Solar and Stellar Astrophysics, Stars: Variables: RR Lyrae, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Dwarf galaxy, Physics, Settore FIS/05, Galaxies: Individual: Eri II, Astronomy and Astrophysics, Horizontal branch, Astrophysics - Astrophysics of Galaxies, Galaxy, Red-giant branch, Star cluster, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Local Group, Astrophysics::Earth and Planetary Astrophysics, Galaxies: Stellar content
Abstract

We present a detailed study of the variable star population of Eridanus II (Eri II), an ultra-faint dwarf galaxy that lies close to the Milky Way virial radius. We analyze multi-epoch $g,r,i$ ground-based data from Goodman and the Dark Energy Camera, plus $F475W, F606W, F814W$ space data from the Advanced Camera for Surveys. We report the detection of 67 RR Lyrae (RRL) stars and 2 Anomalous Cepheids, most of them new discoveries. With the RRL stars, we measure the distance modulus of Eri II, $��_0=22.84\pm 0.05$ mag (D$_{\odot}=370\pm9$ kpc) and derive a metallicity spread of 0.3 dex (0.2 dex intrinsic). The colour distribution of the horizontal branch (HB) and the period distribution of the RRL stars can be nicely reproduced by a combination of two stellar models of [Fe/H]=($-2.62$, $-2.14$). The overall low metallicity is consistent with the red giant branch bump location, 0.65 mag brighter than the HB. These results are in agreement with previous spectroscopic studies. The more metal-rich RRL and the RRab stars have greater central concentration than the more metal-poor RRL and the RRc stars that are mainly located outside $\sim 1$ r$_{\rm h}$. This is similar to what is found in larger dwarf galaxies such as Sculptor, and in agreement with an outside-in galaxy formation scenario. This is remarkable in such a faint dwarf galaxy with an apparently single and extremely short ($, 20 pages, 14 figures, 8 tables. Accepted for publication in MNRAS

Published
2021
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6. Chemical Abundance Analysis of Three α-poor, Metal-poor Stars in the Ultrafaint Dwarf Galaxy Horologium I

Author

R. H. Schindler, E. Balbinot, David J. James, A. Roodman, B. Yanny, E. Suchyta, Darren L. DePoy, T. Jeltema, D. Q. Nagasawa, A. Benoit-Lévy, Alistair R. Walker, W. G. Hartley, M. Carrasco Kind, Marcelle Soares-Santos, R. C. Wolf, Keith Bechtol, G. Gutierrez, Josh Frieman, Risa H. Wechsler, Terese T. Hansen, Jennifer L. Marshall, Elisabeth Krause, J. D. Simon, Enrique Gaztanaga, P. Fosalba, Tianjun Li, Juan Garcia-Bellido, Andrew B. Pace, C. M. Pellegrino, C. B. D'Andrea, S. E. Kuhlmann, Rebecca A. Bernstein, E. Bertin, A. Carnero Rosell, T. F. Eifler, K. Kuehn, F. B. Abdalla, Daniel Thomas, C. J. Davis, David J. Brooks, N. B. Suntzeff, B. Flaugher, Alex Drlica-Wagner, J. Carretero, M. N. K. Smith, T. M. C. Abbott, G. Tarle, J. Gschwend, S. Allam, Robert A. Gruendl, Michael Schubnell, E. J. Sanchez, J. Annis, K. Honscheid, Carlos E. Cunha, Ramon Miquel, B. Nord, S. Desai, R. C. Smith, Flavia Sobreira, Daniel Gruen, M. March, Basilio X. Santiago, D. W. Gerdes, I. Sevilla-Noarbe, N. Kuropatkin, Douglas L. Tucker, L. N. da Costa, V. Scarpine, P. Doel, Louis E. Strigari, Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), DES, UAM. Departamento de Física Teórica, Institut d'Astrophysique de Paris ( IAP ), and Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS )

Subjects
astro-ph.SR, stars: abundances, 010504 meteorology & atmospheric sciences, dwarf [galaxies], astro-ph.GA, Milky Way, Metallicity, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 7. Clean energy, Galactic halo, chemically peculiar [stars], 0103 physical sciences, abundances [galaxies], Astrophysics::Solar and Stellar Astrophysics, Large Magellanic Cloud, 010303 astronomy & astrophysics, STFC, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Dwarf galaxy, Physics, Star formation, RCUK, Física, Astronomy and Astrophysics, galaxies: dwarf, Astrophysics - Astrophysics of Galaxies, stars: chemically peculiar, abundances [stars], Supernova, Stars, Astrophysics - Solar and Stellar Astrophysics, AST-1560223, 13. Climate action, Space and Planetary Science, galaxies: abundances, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Reproduced with permission of AAS, We present chemical abundance measurements of three stars in the ultrafaint dwarf galaxy Horologium I, a Milky Way satellite discovered by the Dark Energy Survey. Using high-resolution spectroscopic observations, we measure the metallicity of the three stars, as well as abundance ratios of several α-elements, iron-peak elements, and neutron-capture elements. The abundance pattern is relatively consistent among all three stars, which have a low average metallicity of [Fe/H] ∼ -2.6 and are not α-enhanced ([α/Fe] ∼ 0.0). This result is unexpected when compared to other low-metallicity stars in the Galactic halo and other ultrafaint dwarfs and suggests the possibility of a different mechanism for the enrichment of Hor I compared to other satellites. We discuss possible scenarios that could lead to this observed nucleosynthetic signature, including extended star formation, enrichment by a Population III supernova, and or an association with the Large Magellanic Cloud, 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 and the Ministério da Ciência, Tecnologia e Inovação, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the Dark Energy Survey. 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

Published
2018
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7. Nearest neighbor:the low-mass Milky Way satellite Tucana III

Author

Enrique J. Fernández, Alex Drlica-Wagner, P. Martini, Michael Schubnell, J. Annis, Daniel Gruen, C. J. Miller, Juan Garcia-Bellido, E. Balbinot, Kyler Kuehn, J. Carretero, Alistair R. Walker, A. Benoit-Lévy, B. Nord, David J. James, Darren L. DePoy, Mei-Yu Wang, T. M. C. Abbott, Jennifer L. Marshall, A. K. Romer, Daniel A. Goldstein, Eric H. Neilsen, D. L. Burke, P. Doel, A. Carnero Rosell, E. J. Sanchez, B. Yanny, Keith Bechtol, S. Allam, G. Gutierrez, A. A. Plazas, E. Buckley-Geer, L. Whiteway, Felipe Menanteau, Joshua A. Frieman, I. Sevilla-Noarbe, E. S. Rykoff, Ramon Miquel, B. Flaugher, Carlos E. Cunha, Robert Connon Smith, N. Kuropatkin, L. N. da Costa, Shantanu Desai, Tianjun Li, M. E. C. Swanson, Flavia Sobreira, C. B. D'Andrea, Basilio X. Santiago, J. D. Simon, Enrique Gaztanaga, M. Carrasco Kind, V. Scarpine, David J. Brooks, G. Tarle, Louis E. Strigari, E. Suchyta, Ricardo L. C. Ogando, M. A. G. Maia, Institut d'Astrophysique de Paris ( IAP ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), DES, Institut d'Astrophysique de Paris (IAP), and Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
individual (Tucana III) [galaxies], Cosmology and Nongalactic Astrophysics (astro-ph.CO), stars: abundances, dwarf [galaxies], Metallicity, Milky Way, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, galaxies: individual, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, dark matter, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Surface brightness, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, STFC, QB, Dwarf galaxy, Physics, 010308 nuclear & particles physics, Velocity dispersion, RCUK, Astronomy and Astrophysics, galaxies: dwarf, stellar content [galaxies], Astrophysics - Astrophysics of Galaxies, Galaxy, Radial velocity, abundances [stars], Space and Planetary Science, Globular cluster, Astrophysics of Galaxies (astro-ph.GA), galaxies: stellar content, Local Group, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite Tucana III (Tuc III). We identify 26 member stars in Tuc III, from which we measure a mean radial velocity of v_hel = -102.3 +/- 0.4 (stat.) +/- 2.0 (sys.) km/s, a velocity dispersion of 0.1^+0.7_-0.1 km/s, and a mean metallicity of [Fe/H] = -2.42^+0.07_-0.08. The upper limit on the velocity dispersion is sigma < 1.5 km/s at 95.5% confidence, and the corresponding upper limit on the mass within the half-light radius of Tuc III is 9.0 x 10^4 Msun. We cannot rule out mass-to-light ratios as large as 240 Msun/Lsun for Tuc III, but much lower mass-to-light ratios that would leave the system baryon-dominated are also allowed. We measure an upper limit on the metallicity spread of the stars in Tuc III of 0.19 dex at 95.5% confidence. Tuc III has a smaller metallicity dispersion and likely a smaller velocity dispersion than any known dwarf galaxy, but a larger size and lower surface brightness than any known globular cluster. Its metallicity is also much lower than those of the clusters with similar luminosity. We therefore tentatively suggest that Tuc III is the tidally-stripped remnant of a dark matter-dominated dwarf galaxy, but additional precise velocity and metallicity measurements will be necessary for a definitive classification. If Tuc III is indeed a dwarf galaxy, it is one of the closest external galaxies to the Sun. Because of its proximity, the most luminous stars in Tuc III are quite bright, including one star at V=15.7 that is the brightest known member star of an ultra-faint satellite., 14 pages, 4 figures (2 in color), 3 tables. Submitted for publication in the AAS Journals

Published
2017
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8. The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. II. UV, Optical, and Near-infrared Light Curves and Comparison to Kilonova Models

Author

P. S. Cowperthwaite, E. Berger, V. A. Villar, B. D. Metzger, M. Nicholl, R. Chornock, P. K. Blanchard, W. Fong, R. Margutti, M. Soares-Santos, K. D. Alexander, S. Allam, J. Annis, D. Brout, D. A. Brown, R. E. Butler, H.-Y. Chen, H. T. Diehl, Z. Doctor, M. R. Drout, T. Eftekhari, B. Farr, D. A. Finley, R. J. Foley, J. A. Frieman, C. L. Fryer, J. García-Bellido, M. S. S. Gill, J. Guillochon, K. Herner, D. E. Holz, D. Kasen, R. Kessler, J. Marriner, T. Matheson, E. H. Neilsen, E. Quataert, A. Palmese, A. Rest, M. Sako, D. M. Scolnic, N. Smith, D. L. Tucker, P. K. G. Williams, E. Balbinot, J. L. Carlin, E. R. Cook, F. Durret, T. S. Li, P. A. A. Lopes, A. C. C. Lourenço, J. L. Marshall, G. E. Medina, J. Muir, R. R. Muñoz, M. Sauseda, D. J. Schlegel, L. F. Secco, A. K. Vivas, W. Wester, A. Zenteno, Y. Zhang, T. M. C. Abbott, M. Banerji, K. Bechtol, A. Benoit-Lévy, E. Bertin, E. Buckley-Geer, D. L. Burke, D. Capozzi, A. Carnero Rosell, M. Carrasco Kind, F. J. Castander, M. Crocce, C. E. Cunha, C. B. D’Andrea, L. N. da Costa, C. Davis, D. L. DePoy, S. Desai, J. P. Dietrich, A. Drlica-Wagner, T. F. Eifler, A. E. Evrard, E. Fernandez, B. Flaugher, P. Fosalba, E. Gaztanaga, D. W. Gerdes, T. Giannantonio, D. A. Goldstein, D. Gruen, R. A. Gruendl, G. Gutierrez, K. Honscheid, B. Jain, D. J. James, T. Jeltema, M. W. G. Johnson, M. D. Johnson, S. Kent, E. Krause, R. Kron, K. Kuehn, N. Nuropatkin, O. Lahav, M. Lima, H. Lin, M. A. G. Maia, M. March, P. Martini, R. G. McMahon, F. Menanteau, C. J. Miller, R. Miquel, J. J. Mohr, E. Neilsen, R. C. Nichol, R. L. C. Ogando, A. A. Plazas, N. Roe, A. K. Romer, A. Roodman, E. S. Rykoff, E. Sanchez, V. Scarpine, R. Schindler, M. Schubnell, I. Sevilla-Noarbe, M. Smith, R. C. Smith, F. Sobreira, E. Suchyta, M. E. C. Swanson, G. Tarle, D. Thomas, R. C. Thomas, M. A. Troxel, V. Vikram, A. R. Walker, R. H. Wechsler, J. Weller, B. Yanny, J. Zuntz, Institut d'Astrophysique de Paris ( IAP ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Institut d'Astrophysique de Paris (IAP), and Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
AST-1714498, neutron star: binary, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], AST-1411763, Astrophysics, Kilonova, 7. Clean energy, 01 natural sciences, Luminosity, star, ultraviolet, site, optical, Astrophysics::Solar and Stellar Astrophysics, LIGO, dark energy, 010303 astronomy & astrophysics, QB, High Energy Astrophysical Phenomena (astro-ph.HE), astro-ph.HE, Physics, binaries: close, HEFCE, gravitational waves, radioactivity, black body, infrared, Spectral energy distribution, Astrophysics - High Energy Astrophysical Phenomena, close [bibaries], Milky Way, Astrophysics::High Energy Astrophysical Phenomena, satellite, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Photometry (optics), stars: neutron, neutron [stars], bolometer, surveys, 0103 physical sciences, capture, STFC, Astrophysics::Galaxy Astrophysics, 010308 nuclear & particles physics, velocity: expansion, gravitational radiation, RCUK, opacity, Astronomy and Astrophysics, Light curve, color, Neutron star, VIRGO, electromagnetic, 13. Climate action, Space and Planetary Science, spectral, galaxy, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], catalogs
Abstract

We present UV, optical, and NIR photometry of the first electromagnetic counterpart to a gravitational wave source from Advanced LIGO/Virgo, the binary neutron star merger GW170817. Our data set extends from the discovery of the optical counterpart at $0.47$ days to $18.5$ days post-merger, and includes observations with the Dark Energy Camera (DECam), Gemini-South/FLAMINGOS-2 (GS/F2), and the {\it Hubble Space Telescope} ({\it HST}). The spectral energy distribution (SED) inferred from this photometry at $0.6$ days is well described by a blackbody model with $T\approx 8300$ K, a radius of $R\approx 4.5\times 10^{14}$ cm (corresponding to an expansion velocity of $v\approx 0.3c$), and a bolometric luminosity of $L_{\rm bol}\approx 5\times10^{41}$ erg s$^{-1}$. At $1.5$ days we find a multi-component SED across the optical and NIR, and subsequently we observe rapid fading in the UV and blue optical bands and significant reddening of the optical/NIR colors. Modeling the entire data set we find that models with heating from radioactive decay of $^{56}$Ni, or those with only a single component of opacity from $r$-process elements, fail to capture the rapid optical decline and red optical/NIR colors. Instead, models with two components consistent with lanthanide-poor and lanthanide-rich ejecta provide a good fit to the data, the resulting "blue" component has $M_\mathrm{ej}^\mathrm{blue}\approx 0.01$ M$_\odot$ and $v_\mathrm{ej}^\mathrm{blue}\approx 0.3$c, and the "red" component has $M_\mathrm{ej}^\mathrm{red}\approx 0.04$ M$_\odot$ and $v_\mathrm{ej}^\mathrm{red}\approx 0.1$c. These ejecta masses are broadly consistent with the estimated $r$-process production rate required to explain the Milky Way $r$-process abundances, providing the first evidence that BNS mergers can be a dominant site of $r$-process enrichment., 13 Pages, 3 Figures, 2 Tables. ApJL, In Press. Keywords: GW170817, LVC

Published
2017
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9. Nearest Neighbor: The Low-mass Milky Way Satellite Tucana III.

Author

J. D. Simon, T. S. Li, A. Drlica-Wagner, K. Bechtol, J. L. Marshall, D. J. James, M. Y. Wang, L. Strigari, E. Balbinot, K. Kuehn, A. R. Walker, T. M. C. Abbott, S. Allam, J. Annis, A. Benoit-Lévy, D. Brooks, E. Buckley-Geer, D. L. Burke, A. Carnero Rosell, and M. Carrasco Kind

Subjects
MILKY Way, DWARF galaxies, STELLAR density (Stellar population), RADIAL velocity of stars, GROUP velocity dispersion, GALACTIC magnitudes
Abstract

We present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite Tucana III (Tuc III). We identify 26 member stars in Tuc III from which we measure a mean radial velocity of vhel = −102.3 ± 0.4 (stat.) ± 2.0 (sys.) , a velocity dispersion of , and a mean metallicity of . The upper limit on the velocity dispersion is σ < 1.5 at 95.5% confidence, and the corresponding upper limit on the mass within the half-light radius of Tuc III is 9.0 × 104M⊙. We cannot rule out mass-to-light ratios as large as 240 M⊙/L⊙ for Tuc III, but much lower mass-to-light ratios that would leave the system baryon-dominated are also allowed. We measure an upper limit on the metallicity spread of the stars in Tuc III of 0.19 dex at 95.5% confidence. Tuc III has a smaller metallicity dispersion and likely a smaller velocity dispersion than any known dwarf galaxy, but a larger size and lower surface brightness than any known globular cluster. Its metallicity is also much lower than those of the clusters with similar luminosity. We therefore tentatively suggest that Tuc III is the tidally stripped remnant of a dark matter-dominated dwarf galaxy, but additional precise velocity and metallicity measurements will be necessary for a definitive classification. If Tuc III is indeed a dwarf galaxy, it is one of the closest external galaxies to the Sun. Because of its proximity, the most luminous stars in Tuc III are quite bright, including one star at V = 15.7 that is the brightest known member star of an ultra-faint satellite. [ABSTRACT FROM AUTHOR]

Published
2017
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10. Farthest Neighbor: The Distant Milky Way Satellite Eridanus II.

Author

T. S. Li, J. D. Simon, A. Drlica-Wagner, K. Bechtol, M. Y. Wang, J. García-Bellido, J. Frieman, J. L. Marshall, D. J. James, L. Strigari, A. B. Pace, E. Balbinot, Y. Zhang, T. M. C. Abbott, S. Allam, A. Benoit-Lévy, G. M. Bernstein, E. Bertin, D. Brooks, and D. L. Burke

Subjects
MILKY Way, GROUP velocity dispersion, LARMOR radius, STELLAR density (Stellar population), RADIAL velocity of stars
Abstract

We present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite Eridanus II (Eri II). We identify 28 member stars in Eri II, from which we measure a systemic radial velocity of and a velocity dispersion of . Assuming that Eri II is a dispersion-supported system in dynamical equilibrium, we derive a mass within the half-light radius of , indicating a mass-to-light ratio of / and confirming that it is a dark matter-dominated dwarf galaxy. From the equivalent width measurements of the Ca triplet lines of 16 red giant member stars, we derive a mean metallicity of [Fe/H] = −2.38 ± 0.13 and a metallicity dispersion of . The velocity of Eri II in the Galactic standard of rest frame is vGSR = −66.6 , indicating that either Eri II is falling into the Milky Way potential for the first time or that it has passed the apocenter of its orbit on a subsequent passage. At a Galactocentric distance of ∼370 kpc, Eri II is one of the Milky Way’s most distant satellites known. Additionally, we show that the bright blue stars previously suggested to be a young stellar population are not associated with Eri II. The lack of gas and recent star formation in Eri II is surprising given its mass and distance from the Milky Way, and may place constraints on models of quenching in dwarf galaxies and on the distribution of hot gas in the Milky Way halo. Furthermore, the large velocity dispersion of Eri II can be combined with the existence of a central star cluster to constrain massive compact halo object dark matter with mass ≳10 . [ABSTRACT FROM AUTHOR]

Published
2017
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11. STELLAR KINEMATICS AND METALLICITIES IN THE ULTRA-FAINT DWARF GALAXY RETICULUM II.

Author

J. D. Simon, A. Drlica-Wagner, T. S. Li, B. Nord, M. Geha, K. Bechtol, E. Balbinot, E. Buckley-Geer, H. Lin, J. Marshall, B. Santiago, L. Strigari, M. Wang, R. H. Wechsler, B. Yanny, T. Abbott, A. H. Bauer, G. M. Bernstein, E. Bertin, and D. Brooks

Subjects
ASTRONOMICAL spectroscopy, NATURAL satellites, STELLAR spectra, DARK matter, RADIAL velocity of galaxies, DWARF galaxies, MILKY Way
Abstract

We present Magellan/M2FS, Very Large Telescope/GIRAFFE, and Gemini South/GMOS spectroscopy of the newly discovered Milky Way satellite Reticulum II. Based on the spectra of 25 Ret II member stars selected from Dark Energy Survey imaging, we measure a mean heliocentric velocity of and a velocity dispersion of . The mass-to-light ratio of Ret II within its half-light radius is , demonstrating that it is a strongly dark matter-dominated system. Despite its spatial proximity to the Magellanic Clouds, the radial velocity of Ret II differs from that of the LMC and SMC by 199 and 83 , respectively, suggesting that it is not gravitationally bound to the Magellanic system. The likely member stars of Ret II span 1.3 dex in metallicity, with a dispersion of 0.28 ± 0.09 dex, and we identify several extremely metal-poor stars with . In combination with its luminosity, size, and ellipticity, these results confirm that Ret II is an ultra-faint dwarf galaxy. With a mean metallicity of , Ret II matches Segue 1 as the most metal-poor galaxy known. Although Ret II is the third-closest dwarf galaxy to the Milky Way, the line-of-sight integral of the dark matter density squared is within 0.°2, indicating that the predicted gamma-ray flux from dark matter annihilation in Ret II is lower than that of several other dwarf galaxies. [ABSTRACT FROM AUTHOR]

Published
2015
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12. EIGHT NEW MILKY WAY COMPANIONS DISCOVERED IN FIRST-YEAR DARK ENERGY SURVEY DATA.

Author

K. Bechtol, A. Drlica-Wagner, E. Balbinot, A. Pieres, J. D. Simon, B. Yanny, B. Santiago, R. H. Wechsler, J. Frieman, A. R. Walker, P. Williams, E. Rozo, E. S. Rykoff, A. Queiroz, E. Luque, A. Benoit-Lévy, D. Tucker, I. Sevilla, R. A. Gruendl, and L. N. da Costa

Subjects
DWARF galaxies, LOCAL Group (Astronomy), GALAXY clusters, MILKY Way, DARK energy
Abstract

We report the discovery of eight new Milky Way companions in of optical imaging data collected during the first year of the Dark Energy Survey (DES). Each system is identified as a statistically significant over-density of individual stars consistent with the expected isochrone and luminosity function of an old and metal-poor stellar population. The objects span a wide range of absolute magnitudes (MV from to ), physical sizes (), and heliocentric distances (). Based on the low surface brightnesses, large physical sizes, and/or large Galactocentric distances of these objects, several are likely to be new ultra-faint satellite galaxies of the Milky Way and/or Magellanic Clouds. We introduce a likelihood-based algorithm to search for and characterize stellar over-densities, as well as identify stars with high satellite membership probabilities. We also present completeness estimates for detecting ultra-faint galaxies of varying luminosities, sizes, and heliocentric distances in the first-year DES data. [ABSTRACT FROM AUTHOR]

Published
2015
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