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25 results on '"Galaxy: kinematics and dynamic"'

1. Deciphering the evolution of the Milky Way discs: Gaia APOGEE Kepler giant stars and the Besan\c{c}on Galaxy Model

Author

J. Montillaud, Nadège Lagarde, N. Cabral, R. Mor, Francesca Figueras, Cristina Chiappini, Friedrich Anders, Andrea Miglio, Céline Reylé, M. Romero-Gómez, Olivier Bienaymé, J.-B. Salomon, David Cornu, Teresa Antoja, Annie C. Robin, Caroline Soubiran, Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut de Science des Matériaux de Mulhouse (IS2M), Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Oregon Health and Science University [Portland] (OHSU), Université de Paris - École de sages-femmes Baudelocque (UP ESF Baudelocque), Université de Paris (UP), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), 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)-CY Cergy Paris Université (CY), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Leibniz-Institut für Astrophysik Potsdam (AIP), Institut de Ciencies del Cosmos (ICCUB), Universitat de Barcelona (UB), University of Birmingham [Birmingham], Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Racah Institute of Physics (Racah Institute of Physics), The Hebrew University of Jerusalem (HUJ)-Racah Institute of Physics, Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), 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), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Ministerio de Ciencia, Innovación y Universidades (España), European Commission, and N. Lagarde, C. Reylé, C. Chiappini, R. Mor, F. Anders, F. Figueras, A. Miglio, M. Romero-Gómez, T. Antoja, N. Cabral, J.-B. Salomon, A.C. Robin, O. Bienaymé, C. Soubiran, D. Cornu, J. Montillaud

Subjects
Stellar population, Metallicity, Milky Way, Population, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Asteroseismology, evolution [Galaxy], 0103 physical sciences, Galaxy formation and evolution, stellar content [Galaxy], education, 010303 astronomy & astrophysics, Galaxy: structure, Astrophysics::Galaxy Astrophysics, Physics, Galaxy: evolution, [PHYS]Physics [physics], education.field_of_study, Galaxy: stellar content, 010308 nuclear & particles physics, Astronomy and Astrophysics, Astrometry, kinematics and dynamics [Galaxy], Astrophysics - Astrophysics of Galaxies, Galaxy, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Galaxy: kinematics and dynamic, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Galaxy: kinematics and dynamics, structure [Galaxy]
Abstract

[Context] Thanks to ongoing efforts to compute accurate stellar ages, we are able to characterise stars in different regions of the Milky Way. The Gaia and Kepler space-missions, along with ground-based spectroscopic surveys such as APOGEE, provide a unique way to study the chemo-kinematics relations as a function of age through the Galactic stellar populations and provide new constraints to Galactic evolution models. [Aims] We investigate the properties of the double sequences of the Milky Way discs visible in the [α/Fe] versus [Fe/H] diagram, which are usually associated to the chemical thin and thick discs at the solar circle. In the framework of Galactic formation and evolution, we discuss the complex relationships between age, metallicity, [α/Fe], and the radial, azimuthal, and vertical components of the space velocities. [Methods] We study stars with measured chemical and seismic properties from the APOGEE spectroscopic survey and the Kepler satellite, respectively. In addition, astrometry from the Gaia satellite is available for the majority of the sample. We separate the [α/Fe]-[Fe/H] diagram into three stellar populations: the thin disc, the high-α metal-poor thick disc, and the high-α metal-rich thick disc and characterise each of these in the age-chemo-kinematics parameter space. Because of the model-dependent nature of the ages inferred from asteroseismology, and because they depend on the quality of the input spectroscopic information, we compare results obtained from different APOGEE data releases (DR14 and DR16). We also use age determinations from two recent works in the literature. In addition, we use the Besançon stellar populations synthesis model to highlight selection biases and mechanisms (such as mergers and secular evolution) not included in the model. [Results] The thin disc exhibits a flat age-metallicity relation while [α/Fe] increases with stellar age. We confirm no correlation between radial and vertical velocities with [Fe/H], [α/Fe], and age for each stellar population. Considering both samples, Vφ decreases with age for the thin disc, while Vφ increases with age for the high-α metal-poor thick disc. We show that this difference is not due to sample selection. Although the age distribution of the high-α metal-rich thick disc is very close to that of the high-α metal-poor thick disc between 7 and 14 Gyr, its kinematics seems to follow that of the thin disc. This feature, not predicted by the hypotheses included in the Besançon Galaxy Model, suggests a different origin and history for this population. Finally, we show that there is a maximum dispersion of the vertical velocity, σZ, with age for the high-α metal-poor thick disc around 8 Gyr. The comparisons with the Besançon Galaxy Model simulations suggest a more complex chemo-dynamical scheme to explain this feature, most likely including mergers and radial migration effects., F.F., A.F., R.M., M.R., T.A. acknowledge support by the Spanish Ministry of Science, Innovation and University (MICIU/FEDER, UE) through grant RTI2018-095076-B-C21, the Institute of Cosmos Sciences University of Barcelona (ICCUB, Unidad de Excelencia “María de Maeztu”) through grant CEX2019-000918-M, the Ramon y Cajal Fellowship RYC2018-025968-I. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 800502. AM acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 772293 – project ASTEROCHRONOMETRY, https://www.asterochronometry.eu.

Published
2021

2. Prospects for Galactic and stellar astrophysics with asteroseismology of giant stars in the TESS continuous viewing zones and beyond

Author

Jennifer L. van Saders, Léo Girardi, Johanna Teske, Emma Willett, Dennis Stello, Tiago L. Campante, M. Vrard, William J. Chaplin, Marc H. Pinsonneault, Savita Mathur, Andreas Christ Sølvsten Jørgensen, Paul G. Beck, Andrea Miglio, Martin Bo Nielsen, B. Mosser, Aldo Serenelli, Thaíse S. Rodrigues, Rafael A. García, Maria Bergemann, Josefina Montalbán, Jamie Tayar, Oliver J. Hall, Sarbani Basu, Luca Casagrande, Domenico Nardiello, Yvonne Elsworth, Rachael L. Beaton, Saniya Khan, Warrick H. Ball, Christina Chiappini, Victor Silva Aguirre, J. Ted Mackereth, Diego Bossini, Government of Canada, University of Toronto, Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Australian Research Council, Generalitat de Catalunya, National Aeronautics and Space Administration (US), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Mackereth, Ted, Miglio, Andrea, Elsworth, Yvonne, Mosser, Benoit, Mathur, Savita, Garcia, Rafael A, Nardiello, Domenico, Hall, Oliver J, Vrard, Mathieu, Ball, Warrick H, Basu, Sarbani, Beaton, Rachael L, Beck, Paul G, Bergemann, Maria, Bossini, Diego, Casagrande, Luca, Campante, Tiago L, Chaplin, William J, Chiappini, Cristina, Girardi, Léo, Jørgensen, Andreas Christ Sølvsten, Khan, Saniya, Montalbán, Josefina, Nielsen, Martin B, Pinsonneault, Marc H, Rodrigues, Thaíse S, Serenelli, Aldo, Silva Aguirre, Victor, Stello, Denni, Tayar, Jamie, Teske, Johanna, van Saders, Jennifer L, and Willett, Emma

Subjects
Red giant, Star (game theory), Milky Way, oscillations [Stars], FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Asteroseismology, fundamental parameters [Stars], 0103 physical sciences, Stars: oscillations, Astrophysics::Solar and Stellar Astrophysics, Asymptotic giant branch, stellar content [Galaxy], 010303 astronomy & astrophysics, Galaxy: structure, Astrophysics::Galaxy Astrophysics, Stars: fundamental parameters, Physics, Galaxy: stellar content, stars: oscillation, 010308 nuclear & particles physics, Star formation, Galaxy: fundamental parameter, fundamental parameters [Galaxy], Astronomy and Astrophysics, stars: fundamental parameter, Galaxy: fundamental parameters, kinematics and dynamics [Galaxy], Giant star, Astrophysics - Astrophysics of Galaxies, Stars, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), Galaxy: kinematics and dynamic, Astrophysics::Earth and Planetary Astrophysics, Galaxy: kinematics and dynamics, structure [Galaxy]
Abstract

Mackereth, J. Ted, et al., The NASA Transiting Exoplanet Survey Satellite (NASA-TESS) mission presents a treasure trove for understanding the stars it observes and the Milky Way, in which they reside. We present a first look at the prospects for Galactic and stellar astrophysics by performing initial asteroseismic analyses of bright (G < 11) red giant stars in the TESS southern continuous viewing zone (SCVZ). Using three independent pipelines, we detect νmax and Δν in 41 per cent of the 15 405 star parent sample (6388 stars), with consistency at a level of ∼2 per cent in νmax and ∼5 per cent in Δν. Based on this, we predict that seismology will be attainable for ∼3 × 105 giants across the whole sky and at least 104 giants with ≥1 yr of observations in the TESS-CVZs, subject to improvements in analysis and data reduction techniques. The best quality TESS-CVZ data, for 5574 stars where pipelines returned consistent results, provide high-quality power spectra across a number of stellar evolutionary states. This makes possible studies of, for example, the asymptotic giant branch bump. Furthermore, we demonstrate that mixed ℓ = 1 modes and rotational splitting are cleanly observed in the 1-yr data set. By combining TESS-CVZ data with TESS-HERMES, SkyMapper, APOGEE, and Gaia, we demonstrate its strong potential for Galactic archaeology studies, providing good age precision and accuracy that reproduces well the age of high [α/Fe] stars and relationships between mass and kinematics from previous studies based on e.g. Kepler. Better quality astrometry and simpler target selection than the Kepler sample makes this data ideal for studies of the local star formation history and evolution of the Galactic disc. These results provide a strong case for detailed spectroscopic follow-up in the CVZs to complement that which has been (or will be) collected by current surveys., JTM and AM acknowledge support from the ERC Consolidator Grant funding scheme (project ASTEROCHRONOMETRY, G.A. n. 772293). JTM acknowledges support from the Banting Postdoctoral Fellowship programme administered by the Government of Canada, and a CITA/Dunlap Institute fellowship. The Dunlap Institute is funded through an endowment established by the David Dunlap family and the University of Toronto. SM acknowledges support from the Spanish Ministry with the Ramon y Cajal fellowship number RYC-2015-17697. RAG acknowledges the support from the PLATO CNES grant. DB acknowledges supported by FCT through the research grants UIDB/04434/2020, UIDP/04434/2020, and PTDC/FIS-AST/30389/2017, and by FEDER – Fundo Europeu de Desenvolvimento Regional through COMPETE2020 – Programa Operacional Competitividade e Internacionalização (grant: POCI-01-0145-FEDER-030389). LC acknowledges support from the Australian Research Council grant FT160100402. TC acknowledges support from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 792848 (PULSATION). AS is partially supported by grants ESP2017-82674-R (Spanish Government) and 2017-SGR-1131 (Generalitat de Catalunya). MHP and MV acknowledge support from NASA grant 80NSSC18K1582.

Published
2021

3. The Milky Way total mass profile as inferred from Gaia DR2

Author

Julio F. Navarro, Marius Cautun, Alejandro Benítez-Llambay, Christine M. Simpson, Kyle A. Oman, Carlos S. Frenk, Facundo A. Gómez, Robert J. J. Grand, Alis J. Deason, Azadeh Fattahi, Cautun, M, Benitez-Llambay, A, Deason, A, Frenk, C, Fattahi, A, Gómez, F, Grand, R, Oman, K, Navarro, J, and Simpson, C

Subjects
Stellar mass, Milky Way, Dark matter, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Galaxy: Structure, Galactic halo, 0103 physical sciences, Galaxy: Halo, 010303 astronomy & astrophysics, Galaxy rotation curve, Astrophysics::Galaxy Astrophysics, Galaxy: Kinematics and dynamic, Physics, Galaxies: Haloe, 010308 nuclear & particles physics, Galaxy: Fundamental parameter, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Baryon, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Halo
Abstract

We determine the Milky Way (MW) mass profile inferred from fitting physically motivated models to the Gaia DR2 Galactic rotation curve and other data. Using various hydrodynamical simulations of MW-mass haloes, we show that the presence of baryons induces a contraction of the dark matter (DM) distribution in the inner regions, r, Comment: 21 pages, 14 figures, main results: figs 3, 7, 10 and 11; MNRAS accepted version, code and resources available at https://github.com/MariusCautun/Milky_Way_mass_profile

Published
2020

4. The orbital phase space of contracted dark matter halos

Author

Marius Cautun, Robert J. J. Grand, Thomas M. Callingham, Alis J. Deason, Ruediger Pakmor, Carlos S. Frenk, Federico Marinacci, Callingham T.M., Cautun M., Deason A.J., Frenk C.S., Grand R.J.J., Marinacci F., and Pakmor R.

Subjects
Milky Way, Dark matter, Dynamic, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Specific relative angular momentum, Galactic halo, 0103 physical sciences, Galaxies: haloe, 010303 astronomy & astrophysics, Galaxy: structure, Astrophysics::Galaxy Astrophysics, Physics, AURIGA, 010308 nuclear & particles physics, Galaxies: kinematic, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy: halo, Baryon, Space and Planetary Science, Phase space, Astrophysics of Galaxies (astro-ph.GA), Galaxy: kinematics and dynamic, Halo
Abstract

We study the orbital phase space of dark matter (DM) haloes in the auriga suite of cosmological hydrodynamics simulations of Milky Way (MW) analogues. We characterize haloes by their spherical action distribution, $F\left(J_{{r}},L\right)$, a function of the specific angular momentum, L, and the radial action, Jr, of the DM particles. By comparing DM-only and hydrodynamical simulations of the same haloes, we investigate the contraction of DM haloes caused by the accumulation of baryons at the centre. We find a small systematic suppression of the radial action in the DM haloes of the hydrodynamical simulations, suggesting that the commonly used adiabatic contraction approximation can result in an underestimate of the density by $\sim 8{{ \rm {per\ cent}}}$. We apply an iterative algorithm to contract the auriga DM haloes given a baryon density profile and halo mass, recovering the true contracted DM profiles with an accuracy of $\sim 15{{ \rm {per\ cent}}}$, that reflects halo-to-halo variation. Using this algorithm, we infer the total mass profile of the MW’s contracted DM halo. We derive updated values for the key astrophysical inputs to DM direct detection experiments: the DM density and velocity distribution in the Solar neighbourhood.

Published
2020
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5. The Pristine Inner Galaxy Survey (PIGS) I: Tracing the kinematics of metal-poor stars in the Galactic bulge

Author

Mathias Schultheis, Jeffrey D. Simpson, Zhen Wan, Anke Arentsen, G. F. Thomas, Nicolas F. Martin, K. A. Venn, Rodrigo A. Ibata, K. Youakim, Daniel B. Zucker, Nicolas Longeard, J. I. González Hernández, Vanessa Hill, Julio F. Navarro, Andrea Kunder, R. G. Carlberg, Carmela Lardo, Khyati Malhan, Geraint F. Lewis, Rubén Sánchez-Janssen, David Aguado, Federico Sestito, Else Starkenburg, Arentsen A., Starkenburg E., Martin N.F., Hill V., Ibata R., Kunder A., Schultheis M., Venn K.A., Zucker D.B., Aguado D., Carlberg R., Gonzalez Hernandez J.I., Lardo C., Longeard N., Malhan K., Navarro J.F., Sanchez-Janssen R., Sestito F., Thomas G., Youakim K., Lewis G.F., Simpson J.D., Wan Z., Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Nice, France., Centre International de Hautes Etudes Agronomiques Méditerranéennes - Institut Agronomique Méditerranéen de Montpellier (CIHEAM-IAMM), Centre International de Hautes Études Agronomiques Méditerranéennes (CIHEAM), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 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, 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), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Toronto, Ecole Polytechnique Fédérale de Lausanne (EPFL), Facultad de Matematicas, Universidad de Murcia, CLRC Daresbury, SFTC, 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), Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), and COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)

Subjects
photometry, Milky Way, Metallicity, bulge -Galaxy, kinematics and dynamics -Galaxy, formation -Galaxy, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Galaxy: Structure, Galactic halo, Galaxy: Evolution, Bulge, 0103 physical sciences, Galaxy formation and evolution, structure, 010303 astronomy & astrophysics, Galaxy: Halo, halo -Galaxy, milky-way, ComputingMilieux_MISCELLANEOUS, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, Galaxy: Kinematics and dynamic, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], stellar populations, Velocity dispersion, Astronomy and Astrophysics, Galaxy: Formation, argos, Galaxy: Bulge, Astrophysics - Astrophysics of Galaxies, Galaxy, evolution -Galaxy, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Stars, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), galaxy: kinematics and dynamics, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Our Galaxy is known to contain a central boxy/peanut-shaped bulge, yet the importance of a classical, pressure-supported component within the central part of the Milky Way is still being debated. It should be most visible at low metallicity, a regime that has not yet been studied in detail. Using metallicity-sensitive narrow-band photometry, the Pristine Inner Galaxy Survey (PIGS) has collected a large sample of metal-poor ([Fe/H] < -1.0) stars in the inner Galaxy to address this open question. We use PIGS to trace the metal-poor inner Galaxy kinematics as function of metallicity for the first time. We find that the rotational signal decreases with decreasing [Fe/H], until it becomes negligible for the most metal-poor stars. Additionally, the velocity dispersion increases with decreasing metallicity for -3.0 < [Fe/H] < -0.5, with a gradient of -44 $\pm$ 4 km$\,$s$^{-1}\,$dex$^{-1}$. These observations may signal a transition between Galactic components of different metallicities and kinematics, a different mapping onto the boxy/peanut-shaped bulge for former disk stars of different metallicities and/or the secular dynamical and gravitational influence of the bar on the pressure-supported component. Our results provide strong constraints on models that attempt to explain the properties of the inner Galaxy., 5 pages + appendices, accepted to MNRAS Letters

Published
2020

6. The dual origin of the Galactic thick disc and halo from the gas-rich Gaia-Enceladus Sausage merger

Author

Francesca Fragkoudi, Azadeh Fattahi, Alis J. Deason, Robert J. J. Grand, Facundo A. Gómez, Daisuke Kawata, Vasily Belokurov, Federico Marinacci, Rüdiger Pakmor, Grand R.J.J., Kawata D., Belokurov V., Deason A.J., Fattahi A., Fragkoudi F., Gomez F.A., Marinacci F., and Pakmor R.

Subjects
Physics, education.field_of_study, Metallicity, Population, Astronomy and Astrophysics, Orbital eccentricity, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galaxy, Stars, Space and Planetary Science, Galaxy: formation, Galaxy formation and evolution, Galaxy: kinematics and dynamic, Halo, Astrophysics::Earth and Planetary Astrophysics, Enceladus, education, Galaxies: spiral, Galaxy: structure, Astrophysics::Galaxy Astrophysics
Abstract

We analyse a set of cosmological magnetohydrodynamic simulations of the formation of Milky Way-mass galaxies identified to have a prominent radially anisotropic stellar halo component similar to the so-called ‘Gaia Sausage’ found in the Gaia data. We examine the effects of the progenitor of the Sausage (the Gaia–Enceladus Sausage, GES) on the formation of major galactic components analogous to the Galactic thick disc and inner stellar halo. We find that the GES merger is likely to have been gas-rich and contribute 10–50 ${{\ \rm per\ cent}}$ of gas to a merger-induced centrally concentrated starburst that results in the rapid formation of a compact, rotationally supported thick disc that occupies the typical chemical thick disc region of chemical abundance space. We find evidence that gas-rich mergers heated the proto-disc of the Galaxy, scattering stars on to less-circular orbits such that their rotation velocity and metallicity positively correlate, thus contributing an additional component that connects the Galactic thick disc to the inner stellar halo. We demonstrate that the level of kinematic heating of the proto-galaxy correlates with the kinematic state of the population before the merger, the progenitor mass, and orbital eccentricity of the merger. Furthermore, we show that the mass and time of the merger can be accurately inferred from local stars on counter-rotating orbits.

Published
2020

7. The cosmological distribution of compact object mergers from dynamical interactions with SMBH binaries

Abstract

We combine sophisticated high-precision scattering experiments, together with results from the Millenium-II simulation, to compute the cosmic merger rate of bound compact object (CO) binaries dynamically interacting with supermassive black hole binaries (SMBHBs). We consider binaries composed of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). The overall merger rates for WD-WD, NS-NS, BH-BH, BH-NS binaries, and EBBH (eccentric binaries of BHs) from redshift ∼5 are found to be 4.32 × 103 yr−1(5.93 × 102 yr−1 for Type Ia SNe), 82.7 yr−1, 96.3 yr−1, 13.1 yr−1, and 148 yr−1, respectively, for a nominal CO binary fraction in the Galactic centre of 0.1. We calculate the distance (R) distribution of the merger sites with respect to the host galaxies of the binaries. The distribution shows a wide range of distances up to ∼Mpc; this tail is produced by escaped hypervelocity CO binaries. Due to the differences in the matter density of the surrounding environment, merger events with different R are expected to display significantly different signatures in their EM counterparts. In particular, merger events (and especially NS-NS) producing a relativistic jet but occurring in the intergalactic medium will have very weak afterglow radiation relative to their prompt emission. These events, which we call 'off-centre', can only be produced from a close encounter between CO binaries and SMBHBs; hence the detection of such merger events would indicate the existence of nearby SMBHBs, and in particular with high mass ratio, produced in the aftermath of a major galaxy merger.

Published
2019

8. Hypervelocity Stars from a Supermassive Black Hole-Intermediate-mass Black Hole Binary

Abstract

In this paper we consider a scenario in which the currently observed hypervelocity stars in our Galaxy have been ejected from the Galactic center as a result of dynamical interactions with an intermediate-mass black hole (IMBH) orbiting the central supermassive black hole (SMBH). By performing three-body scattering experiments, we calculate the distribution of the ejected stars' velocities given various parameters of the IMBH-SMBH binary: IMBH mass, semimajor axis, and eccentricity. We also calculate the rates of change of the BH binary orbital elements due to those stellar ejections. One of our new findings is that the ejection rate depends (although mildly) on the rotation of the stellar nucleus (its total angular momentum). We also compare the ejection velocity distribution with that produced by the Hills mechanism (stellar binary disruption) and find that the latter produces faster stars on average. Also, the IMBH mechanism produces an ejection velocity distribution that is flattened toward the BH binary plane, while the Hills mechanism produces a spherically symmetric one. The results of this paper will allow us in the future to model the ejection of stars by an evolving BH binary and compare both models with Gaia observations, for a wide variety of environments (galactic nuclei, globular clusters, the Large Magellanic Clouds, etc.).

Published
2019

9. The cosmological distribution of compact object mergers from dynamical interactions with SMBH binaries

Author

Rosalba Perna, Alberto Sesana, Yi-Han Wang, Nathan W. C. Leigh, Wang, Y, Leigh, N, Sesana, A, and Perna, R

Subjects
Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Compact star, Galaxy merger, Type (model theory), Solar and Stellar Astrophysics (astro-ph.SR), Galaxies: star clusters: general, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Supermassive black hole, White dwarf, Astronomy and Astrophysics, Stars: kinematics and dynamic, Galaxy: centre, Astrophysics - Astrophysics of Galaxies, Stars: neutron, Galaxy, Redshift, Neutron star, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Galaxy: kinematics and dynamic, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We combine sophisticated high-precision scattering experiments, together with results from the Millenium-II simulation, to compute the cosmic merger rate of bound compact object (CO) binaries dynamically interacting with supermassive black hole binaries (SMBHBs). We consider binaries composed of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). The overall merger rates for WD–WD, NS–NS, BH–BH, BH–NS binaries, and EBBH (eccentric binaries of BHs) from redshift ∼5 are found to be $4.32\times 10^3\, \mathrm{yr}^{-1}(5.93\times 10^2\, \mathrm{yr}^{-1}$ for Type Ia SNe), $82.7\, \mathrm{yr}^{-1}$, $96.3\, \mathrm{yr}^{-1}$, $13.1\, \mathrm{yr}^{-1}$, and $148\, \mathrm{yr}^{-1}$, respectively, for a nominal CO binary fraction in the Galactic centre of 0.1. We calculate the distance (R) distribution of the merger sites with respect to the host galaxies of the binaries. The distribution shows a wide range of distances up to ∼Mpc; this tail is produced by escaped hypervelocity CO binaries. Due to the differences in the matter density of the surrounding environment, merger events with different R are expected to display significantly different signatures in their EM counterparts. In particular, merger events (and especially NS–NS) producing a relativistic jet but occurring in the intergalactic medium will have very weak afterglow radiation relative to their prompt emission. These events, which we call ‘off-centre’, can only be produced from a close encounter between CO binaries and SMBHBs; hence the detection of such merger events would indicate the existence of nearby SMBHBs, and in particular with high mass ratio, produced in the aftermath of a major galaxy merger.

Published
2019

10. Hypervelocity Stars from a Supermassive Black Hole-Intermediate-mass Black Hole binary

Author

Adrian M. Price-Whelan, Alexander Rasskazov, Nathan W. C. Leigh, Elena M. Rossi, Hiromichi Tagawa, Alberto Sesana, Giacomo Fragione, Rasskazov, A, Fragione, G, Leigh, N, Tagawa, H, Sesana, A, Price-Whelan, A, and Rossi, E

Subjects
010504 meteorology & atmospheric sciences, stars: kinematics and dynamics, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Supermassive black hole, Galaxy: center, Galactic Center, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Black hole, Stars, 13. Climate action, Space and Planetary Science, Intermediate-mass black hole, Globular cluster, Astrophysics of Galaxies (astro-ph.GA), Hypervelocity, Galaxy: kinematics and dynamic, Astrophysics::Earth and Planetary Astrophysics
Abstract

In this paper we consider a scenario where the currently observed hypervelocity stars in our Galaxy have been ejected from the Galactic center as a result of dynamical interactions with an intermediate-mass black hole (IMBH) orbiting the central supermassive black hole (SMBH). By performing 3-body scattering experiments, we calculate the distribution of the ejected stars' velocities given various parameters of the IMBH-SMBH binary: IMBH mass, semimajor axis and eccentricity. We also calculate the rates of change of the BH binary orbital elements due to those stellar ejections. One of our new findings is that the ejection rate depends (although mildly) on the rotation of the stellar nucleus (its total angular momentum). We also compare the ejection velocity distribution with that produced by the Hills mechanism (stellar binary disruption) and find that the latter produces faster stars on average. Also, the IMBH mechanism produces an ejection velocity distribution which is flattened towards the BH binary plane while the Hills mechanism produces a spherically symmetric one. The results of this paper will allow us in the future to model the ejection of stars by an evolving BH binary and compare both models with \textit{Gaia} observations, for a wide variety of environments (galactic nuclei, globular clusters, the Large Magellanic Clouds, etc.)., 13 pages, 5 figures, 3 tables, accepted for publication at ApJ

Published
2018

11. Predicting the hypervelocity star population in Gaia

Abstract

Hypervelocity stars (HVSs) are amongst the fastest objects in our Milky Way. These stars are predicted to come from the Galactic centre (GC) and travel along unbound orbits across the Galaxy. In the coming years, the ESA satellite Gaia will provide the most complete and accurate catalogue of the Milky Way, with full astrometric parameters for more than 1 billion stars. In this paper, we present the expected sample size and properties (mass, magnitude, spatial, velocity distributions) of HVSs in the Gaia stellar catalogue. We build three Gaia mock catalogues of HVSs anchored to current observations, exploring different ejection mechanisms and GC stellar population properties. In all cases, we predict hundreds to thousands of HVSs with precise proper motion measurements within a few tens of kpc from us. For stars with a relative error in total proper motion below 10 per cent, the mass range extends to ~10M⊙ but peaks at ~1M⊙. The majority of Gaia HVSs will therefore probe a different mass and distance range compared to the current non-Gaia sample. In addition, a subset of a few hundreds to a few thousands of HVSs with M ~ 3 M⊙ will be bright enough to have a precise measurement of the three-dimensional velocity from Gaia alone. Finally, we show that Gaia will provide more precise proper motion measurements for the current sample of HVS candidates. This will help identifying their birthplace narrowing down their ejection location, and confirming or rejecting their nature as HVSs. Overall, our forecasts are extremely encouraging in terms of quantity and quality of HVS data that can be exploited to constrain both the Milky Way potential and the GC properties.

Published
2018

12. High-speed stars: Galactic hitchhikers

Author

F. Spite, Lorenzo Monaco, Monique Spite, P. Francois, Alessio Mucciarelli, Elisabetta Caffau, M. Haywood, P. Di Matteo, Piercarlo Bonifacio, A. M. Matas Pinto, Luca Sbordone, Caffau E., Monaco L., Bonifacio P., Sbordone L., Haywood M., Spite M., Di Matteo P., Spite F., Mucciarelli A., Francois P., Matas Pinto A.M., Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Universidad Andrés Bello [Santiago] (UNAB), European Southern Observatory [Santiago] (ESO), European Southern Observatory (ESO), and Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)

Subjects
Milky Way, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Blue straggler, 0103 physical sciences, Galaxy formation and evolution, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Galaxy: evolution, Physics, 010308 nuclear & particles physics, Subgiant, Star formation, Stars: abundances, Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Galaxy, Galaxy: halo, Galaxy: abundance, Stars, Galaxy: formation, Space and Planetary Science, Globular cluster, Galaxy: abundances, Galaxy: kinematics and dynamic, Astrophysics::Earth and Planetary Astrophysics, Galaxy: kinematics and dynamics
Abstract

Context.The search for stars born in the very early stages of the Milky Way star formation history is of paramount importance in the study of the early Universe since their chemistry carries irreplaceable information on the conditions in which early star formation and galaxy buildup took place. The search for these objects has generally taken the form of expensive surveys for faint extremely metal-poor stars, the most obvious but not the only candidates to a very early formation.Aims.Thanks toGaiaDR2 radial velocities and proper motions, we identified 72 bright cool stars displaying heliocentric transverse velocities in excess of 500 km s−1. These objects are most likely members of extreme outer-halo populations, either formed in the early Milky Way build-up or accreted from since-destroyed self-gravitating stellar systems.Methods.We analysed low-resolution FORS spectra of the 72 stars in the sample and derived the abundances of a few elements. Despite the large uncertainties on the radial velocity determination, we derived reliable orbital parameters for these objects.Results.The stars analysed are mainly slightly metal poor, with a few very metal-poor stars. Their chemical composition is much more homogeneous than expected. All the stars have very eccentric halo orbits, some extending well beyond the expected dimension of the Milky Way.Conclusions.These stars can be the result of a disrupted small galaxy or they could have been globular cluster members. Age estimates suggest that some of them are evolved blue stragglers, now on the subgiant or asymptotic giant branches.

Published
2020

13. The fraction of dark matter within galaxies from the IllustrisTNG simulations

Author

Mark Vogelsberger, Rainer Weinberger, Dylan Nelson, Adebusola Alabi, Volker Springel, Mark R. Lovell, Paul Torrey, Federico Marinacci, Rüdiger Pakmor, Annalisa Pillepich, Shy Genel, Lars Hernquist, Raunvísindastofnun (HÍ), Science Institute (UI), Verkfræði- og náttúruvísindasvið (HÍ), School of Engineering and Natural Sciences (UI), Háskóli Íslands, University of Iceland, Massachusetts Institute of Technology. Department of Physics, MIT Kavli Institute for Astrophysics and Space Research, Lovell, Mark R., Pillepich, Annalisa, Genel, Shy, Nelson, Dylan, Springel, Volker, Pakmor, Rüdiger, Marinacci, Federico, Weinberger, Rainer, Torrey, Paul, Vogelsberger, Mark, Alabi, Adebusola, and Hernquist, Lars

Subjects
Initial mass function, Milky Way, Dark matter, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, Galaxy: structure, 010303 astronomy & astrophysics, Heimsfræði, Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, dark matter [Cosmology], Astronomy and Astrophysics, Vetrarbrautir, Radius, Astronomy and Astrophysic, kinematics and dynamics [Galaxy], Stjarneðlisfræði, Astrophysics - Astrophysics of Galaxies, Galaxy, Redshift, Baryon, (cosmology:) dark matter, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Elliptical galaxy, Galaxy: kinematics and dynamic, Astrophysics::Earth and Planetary Astrophysics, structure [Galaxy]
Abstract

Publisher's version (útgefin grein), We use the IllustrisTNG (TNG) cosmological simulations to provide theoretical expectations for the dark matter mass fractions (DMFs) and circular velocity profiles of galaxies. TNG predicts flat circular velocity curves for z = 0 Milky Way (MW)-like galaxies beyond a few kpc from the galaxy centre, in better agreement with observational constraints than its predecessor, Illustris. TNG also predicts an enhancement of the dark matter mass within the 3D stellar half-mass radius (⁠rhalf⁠; M200c=1010−1013M⊙⁠, z ≤ 2) compared to its dark matter only and Illustris counterparts. This enhancement leads TNG present-day galaxies to be dominated by dark matter within their inner regions, with fDM(, MRL is supported by a COFUND/Durham Junior Research Fellowship under EU grant 609412. MRL acknowledges support by a Grant of Excellence from the Icelandic Research Fund (grant number 173929-051). VS, RP, and RW acknowledge support through the European Research Council under ERC-StG grant EXAGAL-308037, and would like to thank the Klaus Tschira Foundation. The Flatiron Institute is supported by the Simons Foundation.

Published
2018

14. Gaia Data Release 2. Kinematics of globular clusters and dwarf galaxies around the Milky Way

Author

Helmi, A., van Leeuwen, F., McMillan, P. J., Massari, D., Antoja, T., Robin, A. C., Lindegren, L., Bastian, U., Arenou, F., Babusiaux, C., Biermann, M., Breddels, M. A., Hobbs, D., Jordi, C., Pancino, E., Reyle, C., Veljanoski, J., Brown, A. G. A., Vallenari, A., Prusti, T., de Bruijne, J. H. J., Bailer-Jones, C. A. L., Evans, D. W., Eyer, L., Jansen, F., Klioner, S. A., Lammers, U., Luri, X., Mignard, F., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Siddiqui, H. I., Soubiran, C., Walton, N. A., Cropper, M., Drimmel, R., Katz, D., Lattanzi, M. G., Bakker, J., Cacciari, C., Castaneda, J., Chaoul, L., Cheek, N., De Angeli, F., Fabricius, C., Guerra, R., Holl, B., Masana, E., Messineo, R., Mowlavi, N., Nienartowicz, K., Panuzzo, P., Portell, J., Riello, M., Seabroke, G. M., Tanga, P., Thevenin, F., Gracia-Abril, G., Comoretto, G., Garcia-Reinaldos, M., Teyssier, D., Altmann, M., Andrae, R., Audard, M., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Burgess, P., Busso, G., Carry, B., Cellino, A., Clementini, G., Clotet, M., Creevey, O., Davidson, M., De Ridder, J., Delchambre, L., Dell'Oro, A., Ducourant, C., Fernandez-Hernandez, J., Fouesneau, M., Fremat, Y., Galluccio, L., Garcia-Torres, M., Gonzalez-Nunez, J., Gonzalez-Vidal, J. J., Gosset, E., Guy, L. P., Halbwachs, J. -L., Hambly, N. C., Harrison, D. L., Hernandez, J., Hestroffer, D., Hodgkin, S. T., Hutton, A., Jasniewicz, G., Jean-Antoine-Piccolo, A., Jordan, S., Korn, A. J., Krone-Martins, A., Lanzafame, A. C., Lebzelter, T., Loeffler, W., Manteiga, M., Marrese, P. M., Martin-Fleitas, J. M., Moitinho, A., Mora, A., Muinonen, K., Osinde, J., Pauwels, T., Petit, J. -M., Recio-Blanco, A., Richards, P. J., Rimoldini, L., Sarro, L. M., Siopis, C., Smith, M., Sozzetti, A., Sueveges, M., Torra, J., van Reeven, W., Abbas, U., Abreu Aramburu, A., Accart, S., Aerts, C., Altavilla, G., Alvarez, M. A., Alvarez, R., Alves, J., Anderson, R. I., Andrei, A. H., Anglada Varela, E., Antiche, E., Arcay, B., Astraatmadja, T. L., Bach, N., Baker, S. G., Balaguer-Nunez, L., Balm, P., Barache, C., Barata, C., Barbato, D., Barblan, F., Barklem, P. S., Barrado, D., Barros, M., Barstow, M. A., Bartholome Munoz, S., Bassilana, J. -L., Becciani, U., Bellazzini, M., Berihuete, A., Bertone, S., Bianchi, L., Bienayme, O., Blanco-Cuaresma, S., Boch, T., Boeche, C., Bombrun, A., Borrachero, R., Bossini, D., Bouquillon, S., Bourda, G., Bragaglia, A., Bramante, L., Bressan, A., Brouillet, N., Bruesemeister, T., Brugaletta, E., Bucciarelli, B., Burlacu, A., Busonero, D., Butkevich, A. G., Buzzi, R., Caffau, E., Cancelliere, R., Cannizzaro, G., Cantat-Gaudin, T., Carballo, R., Carlucci, T., Carrasco, J. M., Casamiquela, L., Castellani, M., Castro-Ginard, A., Charlot, P., Chemin, L., Chiavassa, A., Cocozza, G., Costigan, G., Cowell, S., Crifo, F., Crosta, M., Crowley, C., Cuypers, J., Dafonte, C., Damerdji, Y., Dapergolas, A., David, P., David, M., de Laverny, P., De Luise, F., De March, R., de Martino, D., de Souza, R., de Torres, A., Debosscher, J., del Pozo, E., Delbo, M., Delgado, A., Delgado, H. E., Di Matteo, P., Diakite, S., Diener, C., Distefano, E., Dolding, C., Drazinos, P., Duran, J., Edvardsson, B., Enke, H., Eriksson, K., Esquej, P., Bontemps, G. Eynard, Fabre, C., Fabrizio, M., Faigler, S., Falcao, A. J., Farras Casas, M., Federici, L., Fedorets, G., Fernique, P., Figueras, F., Filippi, F., Findeisen, K., Fonti, A., Fraile, E., Fraser, M., Frezouls, B., Gai, M., Galleti, S., Garabato, D., Garcia-Sedano, F., Garofalo, A., Garralda, N., Gavel, A., Gavras, P., Gerssen, J., Geyer, R., Giacobbe, P., Gilmore, G., Girona, S., Giuffrida, G., Glass, F., Gomes, M., Granvik, M., Gueguen, A., Guerrier, A., Guiraud, J., Gutierrez-Sanchez, R., Hofmann, W., Holland, G., Huckle, H. E., Hypki, A., Icardi, V., Janssen, K., de Fombelle, G. Jevardat, Jonker, P. G., Juhasz, A. L., Julbe, F., Karampelas, A., Kewley, A., Klar, J., Kochoska, A., Kohley, R., Kolenberg, K., Kontizas, M., Kontizas, E., Koposov, S. E., Kordopatis, G., Kostrzewa-Rutkowska, Z., Koubsky, P., Lambert, S., Lanza, A. F., Lasne, Y., Lavigne, J. -B., Le Fustec, Y., Le Poncin-Lafitte, C., Lebreton, Y., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Lenhardt, H., Leroux, F., Liao, S., Licata, E., Lindstrom, H. E. P., Lister, T. A., Livanou, E., Lobel, A., Lopez, M., Managau, S., Mann, R. G., Mantelet, G., Marchal, O., Marchant, J. M., Marconi, M., Marinoni, S., Marschalko, G., Marshall, D. J., Martino, M., Marton, G., Mary, N., Matijevic, G., Mazeh, T., Messina, S., Michalik, D., Millar, N. R., Molina, D., Molinaro, R., Molnar, L., Montegriffo, P., Mor, R., Morbidelli, R., Morel, T., Morris, D., Mulone, A. F., Muraveva, T., Musella, I., Nelemans, G., Nicastro, L., Noval, L., O'Mullane, W., Ordenovic, C., Ordonez-Blanco, D., Osborne, P., Pagani, C., Pagano, I., Pailler, F., Palacin, H., Palaversa, L., Panahi, A., Pawlak, M., Piersimoni, A. M., Pineau, F. -X., Plachy, E., Plum, G., Poggio, E., Poujoulet, E., Prsa, A., Pulone, L., Racero, E., Ragaini, S., Rambaux, N., Ramos-Lerate, M., Regibo, S., Riclet, F., Ripepi, V., Riva, A., Rivard, A., Rixon, G., Roegiers, T., Roelens, M., Romero-Gomez, M., Rowell, N., Royer, F., Ruiz-Dern, L., Sadowski, G., Selles, T. Sagrista, Sahlmann, J., Salgado, J., Salguero, E., Sanna, N., Santana-Ros, T., Sarasso, M., Savietto, H., Schultheis, M., Sciacca, E., Segol, M., Segovia, J. C., Segransan, D., Shih, I-C., Siltala, L., Silva, A. F., Smart, R. L., Smith, K. W., Solano, E., Solitro, F., Sordo, R., Soria Nieto, S., Souchay, J., Spagna, A., Spoto, F., Stampa, U., Steele, I. A., Steidelmueller, H., Stephenson, C. A., Stoev, H., Suess, F. F., Surdej, J., Szabados, L., Szegedi-Elek, E., Tapiador, D., Taris, F., Tauran, G., Taylor, M. B., Teixeira, R., Terrett, D., Teyssandier, P., Thuillot, W., Titarenko, A., Torra Clotet, F., Turon, C., Ulla, A., Utrilla, E., Uzzi, S., Vaillant, M., Valentini, G., Valette, V., van Elteren, A., Van Hemelryck, E., van Leeuwen, M., Vaschetto, M., Vecchiato, A., Viala, Y., Vicente, D., Vogt, S., von Essen, C., Voss, H., Votruba, V., Voutsinas, S., Walmsley, G., Weiler, M., Wertz, O., Wevems, T., Wyrzykowski, L., Yoldas, A., Zerjal, M., Ziaeepour, H., Zorec, J., Zschocke, S., Zucker, S., Zurbach, C., Zwitter, T., Collaboration, Gaia, Universidad de Cantabria, Gaia Collaboration, Astronomy, Kapteyn Astronomical Institute, Apollo - University of Cambridge Repository, Helmi, A., Van Leeuwen, F., McMillan, P.J., Massari, D., Antoja, T., Robin, A.C., Lindegren, L., Bastian, U., Arenou, F., Babusiaux, C., Biermann, M., Breddels, M.A., Hobbs, D., Jordi, C., Pancino, E., Reylé, C., Veljanoski, J., Brown, A.G.A., Vallenari, A., Prusti, T., De Bruijne, J.H.J., Bailer-Jones, C.A.L., Evans, D.W., Eyer, L., Jansen, F., Klioner, S.A., Lammers, U., Luri, X., Mignard, F., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Siddiqui, H.I., Soubiran, C., Walton, N.A., Cropper, M., Drimmel, R., Katz, D., Lattanzi, M.G., Bakker, J., Cacciari, C., Castañeda, J., Chaoul, L., Cheek, N., De Angeli, F., Fabricius, C., Guerra, R., Holl, B., Masana, E., Messineo, R., Mowlavi, N., Nienartowicz, K., Panuzzo, P., Portell, J., Riello, M., Seabroke, G.M., Tanga, P., Thévenin, F., Gracia-Abril, G., Comoretto, G., Teyssier, D., Garcia-Reinaldos, M., Altmann, M., Andrae, R., Audard, M., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Burgess, P., Busso, G., Carry, B., Cellino, A., Clementini, G., Clotet, M., Creevey, O., Davidson, M., De Ridder, J., Delchambre, L., Dell'Oro, A., Ducourant, C., Fernández-Hernández, J., Fouesneau, M., Frémat, Y., Galluccio, L., García-Torres, M., González-Núñez, J., González-Vidal, J.J., Gosset, E., Guy, L.P., Halbwachs, J.-L., Hambly, N.C., Harrison, D.L., Hernández, J., Hestroffer, D., Hodgkin, S.T., Hutton, A., Jasniewicz, G., Jean-Antoine-Piccolo, A., Jordan, S., Korn, A.J., Krone-Martins, A., Lanzafame, A.C., Lebzelter, T., Löffler, W., Manteiga, M., Marrese, P.M., Martín-Fleitas, J.M., Moitinho, A., Mora, A., Muinonen, K., Osinde, J., Pauwels, T., Petit, J.-M., Recio-Blanco, A., Richards, P.J., Rimoldini, L., Sarro, L.M., Siopis, C., Smith, M., Sozzetti, A., Söveges, M., Torra, J., Van Reeven, W., Abreu Aramburu, A., Abbas, U., Accart, S., Aerts, C., Altavilla, G., Álvarez, M.A., Alvarez, R., Alves, J., Anderson, R.I., Andrei, A.H., Anglada Varela, E., Antiche, E., Arcay, B., Astraatmadja, T.L., Bach, N., Baker, S.G., Balaguer-Núñez, L., Balm, P., Barache, C., Barata, C., Barbato, D., Barblan, F., Barklem, P.S., Barrado, D., Barros, M., Barstow, M.A., Bartholomé Muñoz, S., Bassilana, J.-L., Becciani, U., Bellazzini, M., Berihuete, A., Bertone, S., Bianchi, L., Bienaymé, O., Blanco-Cuaresma, S., Boch, T., Boeche, C., Bombrun, A., Borrachero, R., Bossini, D., Bouquillon, S., Bourda, G., Bragaglia, A., Bramante, L., Bressan, A., Brouillet, N., Brösemeister, T., Brugaletta, E., Bucciarelli, B., Burlacu, A., Busonero, D., Butkevich, A.G., Buzzi, R., Caffau, E., Cancelliere, R., Cannizzaro, G., Cantat-Gaudin, T., Carballo, R., Carlucci, T., Carrasco, J.M., Casamiquela, L., Castellani, M., Castro-Ginard, A., Charlot, P., Chiavassa, A., Chemin, L., Cocozza, G., Costigan, G., Cowell, S., Crifo, F., Crosta, M., Crowley, C., Cuypersy, J., Dafonte, C., Damerdji, Y., Dapergolas, A., David, P., David, M., De Laverny, P., De Luise, F., De March, R., De Martino, D., De Souza, R., De Torres, A., Debosscher, J., Del Pozo, E., Delbo, M., Delgado, A., Delgado, H.E., Di Matteo, P., Diakite, S., Diener, C., Distefano, E., Dolding, C., Drazinos, P., Durán, J., Edvardsson, B., Enke, H., Eriksson, K., Esquej, P., Eynard Bontemps, G., Fabre, C., Fabrizio, M., Faigler, S., Falcão, A.J., Farràs Casas, M., Federici, L., Fedorets, G., Fernique, P., Figueras, F., Filippi, F., Findeisen, K., Fonti, A., Fraile, E., Fraser, M., Frézouls, B., Gai, M., Galleti, S., Garabato, D., García-Sedano, F., Garofalo, A., Garralda, N., Gavel, A., Gavras, P., Gerssen, J., Geyer, R., Giacobbe, P., Gilmore, G., Giuffrida, G., Girona, S., Glass, F., Gomes, M., Granvik, M., Gueguen, A., Guerrier, A., Guiraud, J., Gutiérrez-Sánchez, R., Hofmann, W., Holland, G., Huckle, H.E., Hypki, A., Icardi, V., Janßen, K., Jevardat De Fombelle, G., Jonker, P.G., Juhász, A.L., Julbe, F., Karampelas, A., Kewley, A., Klar, J., Kochoska, A., Kohley, R., Kolenberg, K., Kontizas, M., Kontizas, E., Koposov, S.E., Kordopatis, G., Kostrzewa-Rutkowska, Z., Koubsky, P., Lambert, S., Lanza, A.F., Lasne, Y., Lavigne, J.-B., Le Fustec, Y., Le Poncin-Lafitte, C., Lebreton, Y., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Lenhardt, H., Leroux, F., Liao, S., Licata, E., Lindstrøm, H.E.P., Lister, T.A., Livanou, E., Lobel, A., López, M., Managau, S., Mann, R.G., Mantelet, G., Marchal, O., Marchant, J.M., Marconi, M., Marinoni, S., Marschalkó, G., Marshall, D.J., Martino, M., Marton, G., Mary, N., Matijevic, G., Mazeh, T., Messina, S., Michalik, D., Millar, N.R., Molina, D., Molinaro, R., Molnár, L., Montegriffo, P., Mor, R., Morbidelli, R., Morel, T., Morris, D., Mulone, A.F., Muraveva, T., Musella, I., Nelemans, G., Nicastro, L., Noval, L., O'Mullane, W., Ordénovic, C., Ordóñez-Blanco, D., Osborne, P., Pagani, C., Pagano, I., Pailler, F., Palacin, H., Palaversa, L., Panahi, A., Pawlak, M., Piersimoni, A.M., Pineau, F.-X., Plachy, E., Plum, G., Poggio, E., Poujoulet, E., Prša, A., Pulone, L., Racero, E., Ragaini, S., Rambaux, N., Ramos-Lerate, M., Regibo, S., Riclet, F., Ripepi, V., Riva, A., Rivard, A., Rixon, G., Roegiers, T., Roelens, M., Romero-Gómez, M., Rowell, N., Royer, F., Ruiz-Dern, L., Sadowski, G., Sagristà Sellés, T., Sahlmann, J., Salgado, J., Salguero, E., Sanna, N., Santana-Ros, T., Sarasso, M., Savietto, H., Schultheis, M., Sciacca, E., Segol, M., Ségransan, D., Segovia, J.C., Shih, I-C., Siltala, L., Silva, A.F., Smart, R.L., Smith, K.W., Solano, E., Solitro, F., Sordo, R., Soria Nieto, S., Souchay, J., Spagna, A., Spoto, F., Stampa, U., Steele, I.A., Steidelmöller, H., Stephenson, C.A., Stoev, H., Suess, F.F., Surdej, J., Szabados, L., Szegedi-Elek, E., Tapiador, D., Taris, F., Tauran, G., Taylor, M.B., Teixeira, R., Terrett, D., Teyssandier, P., Thuillot, W., Titarenko, A., Torra Clotet, F., Turon, C., Ulla, A., Utrilla, E., Uzzi, S., Vaillant, M., Valentini, G., Valette, V., Van Elteren, A., Van Hemelryck, E., Van Leeuwen, M., Vaschetto, M., Vecchiato, A., Viala, Y., Vicente, D., Vogt, S., Von Essen, C., Voss, H., Votruba, V., Voutsinas, S., Walmsley, G., Weiler, M., Wertz, O., Wevems, T., Wyrzykowski, L., Yoldas, A., Žerjal, M., Ziaeepour, H., Zorec, J., Zschocke, S., Zucker, S., Zurbach, C., Zwitter, T., Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Joseph Louis LAGRANGE (LAGRANGE), 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 national de métrologie et d'essais - Systèmes de Référence Temps-Espace (LNE - SYRTE), Systèmes de Référence Temps Espace (SYRTE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-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), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), FORMATION STELLAIRE 2018, 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), M2A 2018, Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), 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), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Department of Physics, Université Nice Sophia Antipolis (... - 2019) (UNS), 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), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), and Universitat de Barcelona

Subjects
Galaxy: kinematics and dynamics / astrometry / globular clusters: general / galaxies: dwarf / Local Group / Magellanic Clouds, dwarf [galaxies], Astronomy, Magellanic Cloud, PROPER MOTIONS, Globular clusters: general, Astrophysics, 01 natural sciences, Catàlegs d'estels, Star catalogs, TO-LIGHT RATIOS, Magellanic Clouds, VELOCITY DISPERSION PROFILE, Large Magellanic Cloud, 010303 astronomy & astrophysics, Galaxy rotation curve, general [globular clusters], Physics, Clusters of galaxies, Galaxies: dwarf, 520 Astronomy, Astrometry, galaxies: dwarf, Local Group, methods: data analysis, astrometry, SPACE VELOCITIES, astrometry, Astrophysics::Earth and Planetary Astrophysics, Galaxy: kinematics and dynamics, GALACTIC HALO, Cúmuls de galàxies, Local Group, Astrometria, EXPLORING HALO SUBSTRUCTURE, Milky Way, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Galaxy: halo, Magellanic Clouds, Settore FIS/05 - Astronomia e Astrofisica, SATELLITE GALAXIES, 0103 physical sciences, DARK-MATTER, globular clusters: general, galaxies: dwarf, Astrophysique, Astrophysics::Galaxy Astrophysics, Dwarf galaxy, Orbital elements, 010308 nuclear & particles physics, Astronomy and Astrophysics, Astronomie, Astronomy and Astrophysic, kinematics and dynamics [Galaxy], Galaxies, 115 Astronomy, Space science, Astrophysics - Astrophysics of Galaxies, Galaxy, Galàxies, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Stars, SPHEROIDAL GALAXY, Space and Planetary Science, Globular cluster, Astrophysics of Galaxies (astro-ph.GA), Galaxy: kinematics and dynamic, LARGE-MAGELLANIC-CLOUD
Abstract

Aims. The goal of this paper is to demonstrate the outstanding quality of the second data release of the Gaia mission and its power for constraining many di erent aspects of the dynamics of the satellites of the Milky Way. We focus here on determining the proper motions of 75 Galactic globular clusters, nine dwarf spheroidal galaxies, one ultra-faint system, and the Large and Small Magellanic Clouds. Methods. Using data extracted from the Gaia archive, we derived the proper motions and parallaxes for these systems, as well as their uncertainties. We demonstrate that the errors, statistical and systematic, are relatively well understood. We integrated the orbits of these objects in three different Galactic potentials, and characterised their properties. We present the derived proper motions, space velocities, and characteristic orbital parameters in various tables to facilitate their use by the astronomical community. Results. Our limited and straightforward analyses have allowed us for example to (i) determine absolute and very precise proper motions for globular clusters; (ii) detect clear rotation signatures in the proper motions of at least five globular clusters; (iii) show that the satellites of the MilkyWay are all on high-inclination orbits, but that they do not share a single plane of motion; (iv) derive a lower limit for the mass of the Milky Way of 9:8$^{+6:7}_{2:7}$ x 10$6{11}$$\odot$ based on the assumption that the Leo I dwarf spheroidal is bound; (v) derive a rotation curve for the Large Magellanic Cloud based solely on proper motions that is competitive with line-of-sight velocity curves, now using many orders of magnitude more sources; and (vi) unveil the dynamical effect of the bar on the motions of stars in the Large Magellanic Cloud. Conclusions. All these results highlight the incredible power of the Gaia astrometric mission, and in particular of its second data release., Includes STFC and ERC.

Published
2018

15. The origin of galactic metal-rich stellar halo components with highly eccentric orbits

Author

Volker Springel, Alis J. Deason, Vasily Belokurov, Federico Marinacci, Rüdiger Pakmor, Carlos S. Frenk, Azadeh Fattahi, Facundo A. Gómez, Robert J. J. Grand, Fattahi, Azadeh, Belokurov, Vasily, Deason, Alis J, Frenk, Carlos S, Gómez, Facundo A, Grand, Robert J J, Marinacci, Federico, Pakmor, Rüdiger, and Springel, Volker

Subjects
Stellar mass, Milky Way, Metallicity, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Galactic halo, 0103 physical sciences, Galaxy formation and evolution, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Dwarf galaxy, Galaxy: evolution, Physics, 010308 nuclear & particles physics, methods: numerical, obsevational, Astronomy and Astrophysics, Astronomy and Astrophysic, Astrophysics - Astrophysics of Galaxies, Galaxy, Galaxy: halo, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Galaxy: kinematics and dynamic, Halo, Astrophysics::Earth and Planetary Astrophysics
Abstract

Using the astrometry from the ESA's Gaia mission, previous works have shown that the Milky Way stellar halo is dominated by metal-rich stars on highly eccentric orbits. To shed light on the nature of this prominent halo component, we have analysed 28 Galaxy analogues in the Auriga suite of cosmological hydrodynamics zoom-in simulations. Some three quarters of the Auriga galaxies contain significant components with high radial velocity anisotropy, beta > 0.6. However, only in one third of the hosts do the high-beta stars contribute significantly to the accreted stellar halo overall, similar to what is observed in the Milky Way. For this particular subset we reveal the origin of the dominant stellar halo component with high metallicity, [Fe/H]~-1, and high orbital anisotropy, beta>0.8, by tracing their stars back to the epoch of accretion. It appears that, typically, these stars come from a single dwarf galaxy with a stellar mass of order of 10^9-10^10 Msol that merged around 6-10 Gyr ago, causing a sharp increase in the halo mass. Our study therefore establishes a firm link between the excess of radially anisotropic stellar debris in the Milky Way halo and an ancient head-on collision between the young Milky Way and a massive dwarf galaxy, replaced with the accepted version (very minor changes)

Published
2018
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16. Mapping the milky way disc kinematics

Author

Katz, D., Antoja, T., Romero-Gomez, M., Drimmel, R., Reyle, C., Seabroke, G. M., Soubiran, C., Babusiaux, C., Di Matteo, P., Figueras, F., Poggio, E., Robin, A. C., Evans, D. W., Brown, A. G. A., Vallenari, A., Prusti, T., De Bruijne, J. H. J., Bailer-Jones, C. A. L., Biermann, M., Eyer, L., Jansen, F., Jordi, C., Klioner, S. A., Lammers, U., Lindegren, L., Luri, X., Mignard, F., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Siddiqui, H. I., Van Leeuwen, F., Walton, N. A., Arenou, F., Bastian, U., Cropper, M., Lattanzi, M. G., Bakker, J., Cacciari, C., Castaneda, J., Chaoul, L., Cheek, N., De Angeli, F., Fabricius, C., Guerra, R., Holl, B., Masana, E., Messineo, R., Mowlavi, N., Nienartowicz, K., Panuzzo, P., Portell, J., Riello, M., Tanga, P., Thevenin, F., Gracia-Abril, G., Comoretto, G., Garcia-Reinaldos, M., Teyssier, D., Altmann, M., Andrae, R., Audard, M., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Burgess, P., Busso, G., Carry, B., Cellino, A., Clementini, G., Clotet, M., Creevey, O., Davidson, M., De Ridder, J., Delchambre, L., Dell'Oro, A., Ducourant, C., Fernandez-Hernandez, J., Fouesneau, M., Fremat, Y., Galluccio, L., Garcia-Torres, M., Gonzalez-Nunez, J., Gonzalez-Vidal, J. J., Gosset, E., Guy, L. P., Halbwachs, J. -L., Hambly, N. C., Harrison, D. L., Hernandez, J., Hestroffer, D., Hodgkin, S. T., Hutton, A., Jasniewicz, G., Jean-Antoine-Piccolo, A., Jordan, S., Korn, A. J., Krone-Martins, A., Lanzafame, A. C., Lebzelter, T., Loffler, W., Manteiga, M., Marrese, P. M., Martin-Fleitas, J. M., Moitinho, A., Mora, A., Muinonen, K., Osinde, J., Pancino, E., Pauwels, T., Petit, J. -M., Recio-Blanco, A., Richards, P. J., Rimoldini, L., Sarro, L. M., Siopis, C., Smith, M., Sozzetti, A., Suveges, M., Torra, J., Van Reeven, W., Abbas, U., Abreu Aramburu, A., Accart, S., Aerts, C., Altavilla, G., Alvarez, M. A., Alvarez, R., Alves, J., Anderson, R. I., Andrei, A. H., Anglada Varela, E., Antiche, E., Arcay, B., Astraatmadja, T. L., Bach, N., Baker, S. G., Balaguer-Nunez, L., Balm, P., Barache, C., Barata, C., Barbato, D., Barblan, F., Barklem, P. S., Barrado, D., Barros, M., Barstow, M. A., Bartholome Munoz, S., Bassilana, J. -L., Becciani, U., Bellazzini, M., Berihuete, A., Bertone, S., Bianchi, L., Bienayme, O., Blanco-Cuaresma, S., Boch, T., Boeche, C., Bombrun, A., Borrachero, R., Bossini, D., Bouquillon, S., Bourda, G., Bragaglia, A., Bramante, L., Breddels, M. A., Bressan, A., Brouillet, N., Brusemeister, T., Brugaletta, E., Bucciarelli, B., Burlacu, A., Busonero, D., Butkevich, A. G., Buzzi, R., Caffau, E., Cancelliere, R., Cannizzaro, G., Cantat-Gaudin, T., Carballo, R., Carlucci, T., Carrasco, J. M., Casamiquela, L., Castellani, M., Castro-Ginard, A., Charlot, P., Chemin, L., Chiavassa, A., Cocozza, G., Costigan, G., Cowell, S., Crifo, F., Crosta, M., Crowley, C., Cuypersy, J., Dafonte, C., Damerdji, Y., Dapergolas, A., David, P., David, M., De Laverny, P., De Luise, F., De March, R., De Souza, R., De Torres, A., Debosscher, J., Del Pozo, E., Delbo, M., Delgado, A., Delgado, H. E., Diakite, S., Diener, C., Distefano, E., Dolding, C., Drazinos, P., Duran, J., Edvardsson, B., Enke, H., Eriksson, K., Esquej, P., Eynard Bontemps, G., Fabre, C., Fabrizio, M., Faigler, S., Falcao, A. J., Farras Casas, M., Federici, L., Fedorets, G., Fernique, P., Filippi, F., Findeisen, K., Fonti, A., Fraile, E., Fraser, M., Frezouls, B., Gai, M., Galleti, S., Garabato, D., Garcia-Sedano, F., Garofalo, A., Garralda, N., Gavel, A., Gavras, P., Gerssen, J., Geyer, R., Giacobbe, P., Gilmore, G., Girona, S., Giuffrida, G., Glass, F., Gomes, M., Granvik, M., Gueguen, A., Guerrier, A., Guiraud, J., Gutierrez-Sanchez, R., Haigron, R., Hatzidimitriou, D., Hauser, M., Haywood, M., Heiter, U., Helmi, A., Heu, J., Hilger, T., Hobbs, D., Hofmann, W., Holland, G., Huckle, H. E., Hypki, A., Icardi, V., Janssen, K., De Fombelle, G. J., Jonker, P. G., Juhasz, A. L., Julbe, F., Karampelas, A., Kewley, A., Klar, J., Kochoska, A., Kohley, R., Kolenberg, K., Kontizas, M., Kontizas, E., Koposov, S. E., Kordopatis, G., Kostrzewa-Rutkowska, Z., Koubsky, P., Lambert, S., Lanza, A. F., Lasne, Y., Lavigne, J. -B., Le Fustec, Y., Le Poncin-Lafitte, C., Lebreton, Y., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Lenhardt, H., Leroux, F., Liao, S., Licata, E., Lindstrom, H. E. P., Lister, T. A., Livanou, E., Lobel, A., Lopez, M., Managau, S., Mann, R. G., Mantelet, G., Marchal, O., Marchant, J. M., Marconi, M., Marinoni, S., Marschalko, G., Marshall, D. J., Martino, M., Marton, G., Mary, N., Massari, D., Matijevic, G., Mazeh, T., Mcmillan, P. J., Messina, S., Michalik, D., Millar, N. R., Molina, D., Molinaro, R., Molnar, L., Montegriffo, P., Mor, R., Morbidelli, R., Morel, T., Morris, D., Mulone, A. F., Muraveva, T., Musella, I., Nelemans, G., Nicastro, L., Noval, L., O'Mullane, W., Ordenovic, C., Ordonez-Blanco, D., Osborne, P., Pagani, C., Pagano, I., Pailler, F., Palacin, H., Palaversa, L., Panahi, A., Pawlak, M., Piersimoni, A. M., Pineau, F. -X., Plachy, E., Plum, G., Poujoulet, E., Prsa, A., Pulone, L., Racero, E., Ragaini, S., Rambaux, N., Ramos-Lerate, M., Regibo, S., Riclet, F., Ripepi, V., Riva, A., Rivard, A., Rixon, G., Roegiers, T., Roelens, M., Rowell, N., Royer, F., Ruiz-Dern, L., Sadowski, G., Sagrista Selles, T., Sahlmann, J., Salgado, J., Salguero, E., Sanna, N., Santana-Ros, T., Sarasso, M., Savietto, H., Schultheis, M., Sciacca, E., Segol, M., Segovia, J. C., Segransan, D., Shih, I. -C., Siltala, L., Silva, A. F., Smart, R. L., Smith, K. W., Solano, E., Solitro, F., Sordo, R., Soria Nieto, S., Souchay, J., Spagna, A., Spoto, F., Stampa, U., Steele, I. A., Steidelmuller, H., Stephenson, C. A., Stoev, H., Suess, F. F., Surdej, J., Szabados, L., Szegedi-Elek, E., Tapiador, D., Taris, F., Tauran, G., Taylor, M. B., Teixeira, R., Terrett, D., Teyssandier, P., Thuillot, W., Titarenko, A., Torra Clotet, F., Turon, C., Ulla, A., Utrilla, E., Uzzi, S., Vaillant, M., Valentini, G., Valette, V., Van Elteren, A., Van Hemelryck, E., Van Leeuwen, M., Vaschetto, M., Vecchiato, A., Veljanoski, J., Viala, Y., Vicente, D., Vogt, S., Von Essen, C., Voss, H., Votruba, V., Voutsinas, S., Walmsley, G., Weiler, M., Wertz, O., Wevers, T., Wyrzykowski, L., Yoldas, A., Zerjal, M., Ziaeepour, H., Zorec, J., Zschocke, S., Zucker, S., Zurbach, C., Zwitter, T., Katz, D., Antoja, T., Romero-Gómez, M., Drimmel, R., Reylé, C., Seabroke, G.M., Soubiran, C., Babusiaux, C., Di Matteo, P., Figueras, F., Poggio, E., Robin, A.C., Evans, D.W., Brown, A.G.A., Vallenari, A., Prusti, T., De Bruijne, J.H.J., Bailer-Jones, C.A.L., Biermann, M., Eyer, L., Jansen, F., Jordi, C., Klioner, S.A., Lammers, U., Lindegren, L., Luri, X., Mignard, F., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Siddiqui, H.I., Van Leeuwen, F., Walton, N.A., Arenou, F., Bastian, U., Cropper, M., Lattanzi, M.G., Bakker, J., Cacciari, C., Castañeda, J., Chaoul, L., Cheek, N., De Angeli, F., Fabricius, C., Guerra, R., Holl, B., Masana, E., Messineo, R., Mowlavi, N., Nienartowicz, K., Panuzzo, P., Portell, J., Riello, M., Tanga, P., Thévenin, F., Gracia-Abril, G., Comoretto, G., Garcia-Reinaldos, M., Teyssier, D., Altmann, M., Andrae, R., Audard, M., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Burgess, P., Busso, G., Carry, B., Cellino, A., Clementini, G., Clotet, M., Creevey, O., Davidson, M., De Ridder, J., Delchambre, L., Dell'Oro, A., Ducourant, C., Fernández-Hernández, J., Fouesneau, M., Frémat, Y., Galluccio, L., García-Torres, M., González-Núñez, J., González-Vidal, J.J., Gosset, E., Guy, L.P., Halbwachs, J.-L., Hambly, N.C., Harrison, D.L., Hernández, J., Hestroffer, D., Hodgkin, S.T., Hutton, A., Jasniewicz, G., Jean-Antoine-Piccolo, A., Jordan, S., Korn, A.J., Krone-Martins, A., Lanzafame, A.C., Lebzelter, T., Löffler, W., Manteiga, M., Marrese, P.M., Martín-Fleitas, J.M., Moitinho, A., Mora, A., Muinonen, K., Osinde, J., Pancino, E., Pauwels, T., Petit, J.-M., Recio-Blanco, A., Richards, P.J., Rimoldini, L., Sarro, L.M., Siopis, C., Smith, M., Sozzetti, A., Süveges, M., Torra, J., Van Reeven, W., Abbas, U., Abreu Aramburu, A., Accart, S., Aerts, C., Altavilla, G., Álvarez, M.A., Alvarez, R., Alves, J., Anderson, R.I., Andrei, A.H., Anglada Varela, E., Antiche, E., Arcay, B., Astraatmadja, T.L., Bach, N., Baker, S.G., Balaguer-Núñez, L., Balm, P., Barache, C., Barata, C., Barbato, D., Barblan, F., Barklem, P.S., Barrado, D., Barros, M., Barstow, M.A., Bartholomé Muñoz, S., Bassilana, J.-L., Becciani, U., Bellazzini, M., Berihuete, A., Bertone, S., Bianchi, L., Bienaymé, O., Blanco-Cuaresma, S., Boch, T., Boeche, C., Bombrun, A., Borrachero, R., Bossini, D., Bouquillon, S., Bourda, G., Bragaglia, A., Bramante, L., Breddels, M.A., Bressan, A., Brouillet, N., Brüsemeister, T., Brugaletta, E., Bucciarelli, B., Burlacu, A., Busonero, D., Butkevich, A.G., Buzzi, R., Caffau, E., Cancelliere, R., Cannizzaro, G., Cantat-Gaudin, T., Carballo, R., Carlucci, T., Carrasco, J.M., Casamiquela, L., Castellani, M., Castro-Ginard, A., Charlot, P., Chemin, L., Chiavassa, A., Cocozza, G., Costigan, G., Cowell, S., Crifo, F., Crosta, M., Crowley, C., Cuypersy, J., Dafonte, C., Damerdji, Y., Dapergolas, A., David, P., David, M., De Laverny, P., De Luise, F., De March, R., De Souza, R., De Torres, A., Debosscher, J., Del Pozo, E., Delbo, M., Delgado, A., Delgado, H.E., Diakite, S., Diener, C., Distefano, E., Dolding, C., Drazinos, P., Durán, J., Edvardsson, B., Enke, H., Eriksson, K., Esquej, P., Eynard Bontemps, G., Fabre, C., Fabrizio, M., Faigler, S., Falcão, A.J., Farràs Casas, M., Federici, L., Fedorets, G., Fernique, P., Filippi, F., Findeisen, K., Fonti, A., Fraile, E., Fraser, M., Frézouls, B., Gai, M., Galleti, S., Garabato, D., García-Sedano, F., Garofalo, A., Garralda, N., Gavel, A., Gavras, P., Gerssen, J., Geyer, R., Giacobbe, P., Gilmore, G., Girona, S., Giuffrida, G., Glass, F., Gomes, M., Granvik, M., Gueguen, A., Guerrier, A., Guiraud, J., Gutiérrez-Sánchez, R., Haigron, R., Hatzidimitriou, D., Hauser, M., Haywood, M., Heiter, U., Helmi, A., Heu, J., Hilger, T., Hobbs, D., Hofmann, W., Holland, G., Huckle, H.E., Hypki, A., Icardi, V., Janßen, K., De Fombelle, G. Jevardat, Jonker, P.G., Juhász, Ã .L., Julbe, F., Karampelas, A., Kewley, A., Klar, J., Kochoska, A., Kohley, R., Kolenberg, K., Kontizas, M., Kontizas, E., Koposov, S.E., Kordopatis, G., Kostrzewa-Rutkowska, Z., Koubsky, P., Lambert, S., Lanza, A.F., Lasne, Y., Lavigne, J.-B., Le Fustec, Y., Le Poncin-Lafitte, C., Lebreton, Y., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Lenhardt, H., Leroux, F., Liao, S., Licata, E., Lindstrøm, H.E.P., Lister, T.A., Livanou, E., Lobel, A., López, M., Managau, S., Mann, R.G., Mantelet, G., Marchal, O., Marchant, J.M., Marconi, M., Marinoni, S., Marschalkó, G., Marshall, D.J., Martino, M., Marton, G., Mary, N., Massari, D., Matijević, G., Mazeh, T., McMillan, P.J., Messina, S., Michalik, D., Millar, N.R., Molina, D., Molinaro, R., Molnár, L., Montegriffo, P., Mor, R., Morbidelli, R., Morel, T., Morris, D., Mulone, A.F., Muraveva, T., Musella, I., Nelemans, G., Nicastro, L., Noval, L., O'Mullane, W., Ordénovic, C., Ordóñez-Blanco, D., Osborne, P., Pagani, C., Pagano, I., Pailler, F., Palacin, H., Palaversa, L., Panahi, A., Pawlak, M., Piersimoni, A.M., Pineau, F.-X., Plachy, E., Plum, G., Poujoulet, E., Prša, A., Pulone, L., Racero, E., Ragaini, S., Rambaux, N., Ramos-Lerate, M., Regibo, S., Riclet, F., Ripepi, V., Riva, A., Rivard, A., Rixon, G., Roegiers, T., Roelens, M., Rowell, N., Royer, F., Ruiz-Dern, L., Sadowski, G., Sagristà Sellés, T., Sahlmann, J., Salgado, J., Salguero, E., Sanna, N., Santana-Ros, T., Sarasso, M., Savietto, H., Schultheis, M., Sciacca, E., Segol, M., Segovia, J.C., Ségransan, D., Shih, I.-C., Siltala, L., Silva, A.F., Smart, R.L., Smith, K.W., Solano, E., Solitro, F., Sordo, R., Soria Nieto, S., Souchay, J., Spagna, A., Spoto, F., Stampa, U., Steele, I.A., Steidelmüller, H., Stephenson, C.A., Stoev, H., Suess, F.F., Surdej, J., Szabados, L., Szegedi-Elek, E., Tapiador, D., Taris, F., Tauran, G., Taylor, M.B., Teixeira, R., Terrett, D., Teyssandier, P., Thuillot, W., Titarenko, A., Torra Clotet, F., Turon, C., Ulla, A., Utrilla, E., Uzzi, S., Vaillant, M., Valentini, G., Valette, V., Van Elteren, A., Van Hemelryck, E., Van Leeuwen, M., Vaschetto, M., Vecchiato, A., Veljanoski, J., Viala, Y., Vicente, D., Vogt, S., Von Essen, C., Voss, H., Votruba, V., Voutsinas, S., Walmsley, G., Weiler, M., Wertz, O., Wevers, T., Wyrzykowski, Å ., Yoldas, A., Žerjal, M., Ziaeepour, H., Zorec, J., Zschocke, S., Zucker, S., Zurbach, C., and Zwitter, T.

Subjects
Solar neighborhood, Space and Planetary Science, Galaxy: kinematics and dynamic, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy and Astrophysic, Galaxy: kinematics and dynamics, Astrophysics::Galaxy Astrophysics, Galaxy: disk
Abstract

Context. The second Gaia data release (Gaia DR2) contains high-precision positions, parallaxes, and proper motions for 1.3 billion sources as well as line-of-sight velocities for 7.2 million stars brighter than GRVS = 12 mag. Both samples provide a full sky coverage. Aims. To illustrate the potential of Gaia DR2, we provide a first look at the kinematics of the Milky Way disc, within a radius of several kiloparsecs around the Sun. Methods. We benefit for the first time from a sample of 6.4 million F-G-K stars with full 6D phase-space coordinates, precise parallaxes (σω/ω/≤ 20%), and precise Galactic cylindrical velocities (median uncertainties of 0.9-1.4 km s-1 and 20% of the stars with uncertainties smaller than 1 km s-1 on all three components). From this sample, we extracted a sub-sample of 3.2 million giant stars to map the velocity field of the Galactic disc from ∼5 kpc to ∼13 kpc from the Galactic centre and up to 2 kpc above and below the plane. We also study the distribution of 0.3 million solar neighbourhood stars (r < 200 pc), with median velocity uncertainties of 0.4 km s-1, in velocity space and use the full sample to examine how the over-densities evolve in more distant regions. Results. Gaia DR2 allows us to draw 3D maps of the Galactocentric median velocities and velocity dispersions with unprecedented accuracy, precision, and spatial resolution. The maps show the complexity and richness of the velocity field of the galactic disc. We observe streaming motions in all the components of the velocities as well as patterns in the velocity dispersions. For example, we confirm the previously reported negative and positive galactocentric radial velocity gradients in the inner and outer disc, respectively. Here, we see them as part of a non-axisymmetric kinematic oscillation, and we map its azimuthal and vertical behaviour. We also witness a new global arrangement of stars in the velocity plane of the solar neighbourhood and in distant regions in which stars are organised in thin substructures with the shape of circular arches that are oriented approximately along the horizontal direction in the U - V plane. Moreover, in distant regions, we see variations in the velocity substructures more clearly than ever before, in particular, variations in the velocity of the Hercules stream. Conclusions. Gaia DR2 provides the largest existing full 6D phase-space coordinates catalogue. It also vastly increases the number of available distances and transverse velocities with respect to Gaia DR1. Gaia DR2 offers a great wealth of information on the Milky Way and reveals clear non-axisymmetric kinematic signatures within the Galactic disc, for instance. It is now up to the astronomical community to explore its full potential.

Published
2018

17. The Gaia-ESO Survey: Churning through the Milky Way

Author

Carmela Lardo, Sofia Feltzing, Vanessa Hill, Laura Magrini, Amelia Bayo, Gerard Gilmore, P. de Laverny, S. Mikolaitis, Paula Jofre, A. Hourihane, E. Franciosini, Michael R. Hayden, Alejandra Recio-Blanco, Elena Pancino, Georges Kordopatis, Thomas Bensby, E. Stonkute, G. G. Sacco, Sofia Randich, Karin Lind, Angela Bragaglia, M. T. Costado, L. Morbidelli, Maria Bergemann, Sergey E. Koposov, A. C. Lanzafame, Jack Lewis, Guillaume Guiglion, Tomaž Zwitter, Andrew R. Casey, Lorenzo Monaco, C. C. Worley, Agence Nationale de la Recherche (France), Knut and Alice Wallenberg Foundation, European Southern Observatory, Science and Technology Facilities Council (UK), European Research Council, Leverhulme Trust, Istituto Nazionale di Astrofisica, Ministero dell'Istruzione, dell'Università e della Ricerca, European Science Foundation, 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), Institute of Astronomy [Cambridge], University of Cambridge [UK] (CAM), INAF - Osservatorio Astronomico di Bologna (OABO), Istituto Nazionale di Astrofisica (INAF), Lund Observatory, Lund University [Lund], INAF - Osservatorio Astrofisico di Catania (OACT), Ecole Polytechnique Fédérale de Lausanne (EPFL), Max-Planck-Institut für Astrophysik (MPA), Max-Planck-Gesellschaft, Istituto Nazionale di Fisica Nucleare, Sezione di Milano (INFN), Istituto Nazionale di Fisica Nucleare (INFN), University of Ljubljana, Hayden M.R., Recio-Blanco A., De Laverny P., Mikolaitis S., Guiglion G., Hill V., Gilmore G., Randich S., Bayo A., Bensby T., Bergemann M., Bragaglia A., Casey A., Costado M., Feltzing S., Franciosini E., Hourihane A., Jofre P., Koposov S., Kordopatis G., Lanzafame A., Lardo C., Lewis J., Lind K., Magrini L., Monaco L., Morbidelli L., Pancino E., Sacco G., Stonkute E., Worley C.C., Zwitter T., Gilmore, Gerard [0000-0003-4632-0213], Worley, Clare [0000-0001-9310-2898], and Apollo - University of Cambridge Repository

Subjects
astro-ph.GA, Metallicity, Milky Way, FOS: Physical sciences, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Galaxy: disk, Astronomi, astrofysik och kosmologi, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astronomy, Astrophysics and Cosmology, stellar content [Galaxy], Galaxy: structure, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Orbital elements, Physics, Galaxy: stellar content, 010308 nuclear & particles physics, Velocity dispersion, Astronomy and Astrophysics, kinematics and dynamics [Galaxy], Astrophysics - Astrophysics of Galaxies, Galaxy, Galaxy: kinematics and dynamics, Space and Planetary Science, Radial velocity, Stars, 13. Climate action, Astrophysics of Galaxies (astro-ph.GA), Galaxy: kinematics and dynamic, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], disk [Galaxy], structure [Galaxy]
Abstract

Context. There have been conflicting results with respect to the extent that radial migration has played in the evolution of the Galaxy. Additionally, observations of the solar neighborhood have shown evidence of a merger in the past history of the Milky Way that drives enhanced radial migration. Aims. We attempt to determine the relative fraction of stars that have undergone significant radial migration by studying the orbital properties of metal-rich ([Fe/H] > 0.1) stars within 2 kpc of the Sun. We also aim to investigate the kinematic properties, such as velocity dispersion and orbital parameters, of stellar populations near the Sun as a function of [Mg/Fe] and [Fe/H], which could show evidence of a major merger in the past history of the Milky Way. Methods. We used a sample of more than 3000 stars selected from the fourth internal data release of the Gaia-ESO Survey. We used the stellar parameters from the Gaia-ESO Survey along with proper motions from PPMXL to determine distances, kinematics, and orbital properties for these stars to analyze the chemodynamic properties of stellar populations near the Sun. Results. Analyzing the kinematics of the most metal-rich stars ([Fe/H] > 0.1), we find that more than half have small eccentricities (e< 0.2) or are on nearly circular orbits. Slightly more than 20% of the metal-rich stars have perigalacticons R> 7 kpc. We find that the highest [Mg/Fe], metal-poor populations have lower vertical and radial velocity dispersions compared to lower [Mg/Fe] populations of similar metallicity by ~10 km s. The median eccentricity increases linearly with [Mg/Fe] across all metallicities, while the perigalacticon decreases with increasing [Mg/Fe] for all metallicities. Finally, the most [Mg/Fe]-rich stars are found to have significant asymmetric drift and rotate more than 40 km s slower than stars with lower [Mg/Fe] ratios. Conclusions. While our results cannot constrain how far stars have migrated, we propose that migration processes are likely to have played an important role in the evolution of the Milky Way, with metal-rich stars migrating from the inner disk toward to solar neighborhood and past mergers potentially driving enhanced migration of older stellar populations in the disk.© ESO, 2018., The authors thank Ivan Minchev for a useful discussion and the anonymous referee for useful comments. M.R.H. and A.R.B. received financial support from ANR, reference 14-CE33-0014-01. S.F. and T.B. acknowledge support from the project grant >The New Milky Way> from the Knut and Alice Wallenberg Foundation. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under program ID 188.B-3002. These data products have been processed by the Cambridge Astronomy Survey Unit (CASU) at the Institute of Astronomy, University of Cambridge, and by the FLAMES/UVES reduction team at INAF/Osservatorio Astrofisico di Arcetri. These data have been obtained from the Gaia-ESO Survey Data Archive, prepared and hosted by the Wide Field Astronomy Unit, Institute for Astronomy, University of Edinburgh, which is funded by the UK Science and Technology Facilities Council. This work was partly supported by the European Union FP7 programme through ERC grant number 320360 and by the Leverhulme Trust through grant RPG-2012-541. We acknowledge the support from INAF and Ministero dell' Istruzione, dell' Universita' e della Ricerca (MIUR) in the form of the grant >Premiale VLT 2012>. The results presented here benefit from discussions held during the Gaia-ESO workshops and conferences supported by the ESF (European Science Foundation) through the GREAT Research Network Programme. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France and NASA's Astrophysics Data System.

Published
2018

18. Predicting the hypervelocity star population in Gaia

Author

T. Marchetti, J.G. Albert, Elena M. Rossi, O. Contigiani, Anthony G. A. Brown, Alberto Sesana, Marchetti, T, Contigiani, O, Rossi, E, Albert, J, Brown, A, and Sesana, A

Subjects
Proper motion, Stellar population, Milky Way, Population, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Catalogue, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, education, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, education.field_of_study, Methods: numerical, 010308 nuclear & particles physics, Galactic Center, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Galaxy: centre, Astrophysics - Astrophysics of Galaxies, Galaxy, Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Magnitude (astronomy), Galaxy: kinematics and dynamic, Astrophysics::Earth and Planetary Astrophysics
Abstract

Hypervelocity stars (HVSs) are amongst the fastest objects in our Milky Way. These stars are predicted to come from the Galactic center (GC) and travel along unbound orbits across the Galaxy. In the coming years, the ESA satellite Gaia will provide the most complete and accurate catalogue of the Milky Way, with full astrometric parameters for more than $1$ billion stars. In this paper, we present the expected sample size and properties (mass, magnitude, spatial, velocity distributions) of HVSs in the Gaia stellar catalogue. We build three Gaia mock catalogues of HVSs anchored to current observations, exploring different ejection mechanisms and GC stellar population properties. In all cases, we predict hundreds to thousands of HVSs with precise proper motion measurements within a few tens of kpc from us. For stars with a relative error in total proper motion below $10 \%$, the mass range extends to ~$10 M_{\odot}$ but peaks at ~$1$ $M_\odot$. The majority of Gaia HVSs will therefore probe a different mass and distance range compared to the current non-Gaia sample. In addition, a subset of a few hundreds to a few thousands of HVSs with $M$ ~ $3$ $M_\odot$ will be bright enough to have a precise measurement of the three-dimensional velocity from Gaia alone. Finally, we show that Gaia will provide more precise proper motion measurements for the current sample of HVS candidates. This will help identifying their birthplace narrowing down their ejection location, and confirming or rejecting their nature as HVSs. Overall, our forecasts are extremely encouraging in terms of quantity and quality of HVS data that can be exploited to constrain both the Milky Way potential and the GC properties., 17 pages, 18 figures, accepted for publication in MNRAS

Published
2017

19. Origin of the system of globular clusters in the Milky Way

Author

Helmer H. Koppelman, Amina Helmi, Davide Massari, Astronomy, and Davide Massari, H.H. Koppelman, A. Helmi

Subjects
DYNAMICS, Milky Way, PROPER MOTIONS, Globular clusters: general, FOS: Physical sciences, Context (language use), Astrophysics, 01 natural sciences, Galaxy groups and clusters, HISTORY, 0103 physical sciences, Galaxy formation and evolution, Cluster (physics), STREAMS, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Dwarf galaxy, Galaxy: evolution, Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, galaxies: dwarf, Astrophysics - Astrophysics of Galaxies, AGES, Galaxy, GALAXY, Galaxy: formation, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Globular cluster, HALO, SPACE VELOCITIES, Galaxy: kinematics and dynamic, SATELLITES, Galaxy: kinematics and dynamics
Abstract

$Context$. The assembly history experienced by the Milky Way is currently being unveiled thanks to the data provided by the $Gaia$ mission. It is likely that the globular cluster system of our Galaxy has followed a similarly intricate formation path. $Aims$. To constrain this formation path, we explore the link between the globular clusters and the known merging events that the Milky Way has experienced. $Methods$. To this end, we combined the kinematic information provided by $Gaia$ for almost all Galactic clusters, with the largest sample of cluster ages available after carefully correcting for systematic errors. To identify clusters with a common origin we analysed their dynamical properties, particularly in the space of integrals of motion. $Results$. We find that about 40% of the clusters likely formed in situ. A similarly large fraction, 35%, appear to be possibly associated to known merger events, in particular to $Gaia$-Enceladus (19%), the Sagittarius dwarf galaxy (5%), the progenitor of the Helmi streams (6%), and to the Sequoia galaxy (5%), although some uncertainty remains due to the degree of overlap in their dynamical characteristics. Of the remaining clusters, 16% are tentatively associated to a group with high binding energy, while the rest are all on loosely bound orbits and likely have a more heterogeneous origin. The resulting age-metallicity relations are remarkably tight and differ in their detailed properties depending on the progenitor, providing further confidence on the associations made. $Conclusions$. We provide a table listing the likely associations. Improved kinematic data by future Gaia data releases and especially a larger, systematic error-free sample of cluster ages would help to further solidify our conclusions., Comment: 8 pages, 5 figures, accepted for publication by A&A Letters. The list of all globular clusters and their associated progenitors is provided in Table 1 in the Appendix

Published
2019

20. DISPERSAL of TIDAL DEBRIS in A MILKY-WAY-SIZED DARK MATTER HALO

Abstract

We simulate the tidal disruption of a collisionless N-body globular star cluster in a total of 300 different orbits selected to have galactocentric radii between 10 and 30 kpc in four dark matter halos: (a) a spherical halo with no subhalos, (b) a spherical halo with subhalos, (c) a realistic halo with no subhalos, and (d) a realistic halo with subhalos. This allows us to isolate and study how the halo's (lack of) dynamical symmetry and substructures affect the dispersal of tidal debris. The realistic halos are constructed from the snapshot of the Via Lactea II simulation at redshift zero. We find that the overall halo's symmetry disperses tidal debris to make the streams fluffier, consistent with previous studies of tidal debris of dwarf galaxies in larger orbits than ours in this study. On the other hand, subhalos in realistic potentials can locally enhance the densities along streams, making streams denser than their counterparts in smooth potentials. We show that many long and thin streams can survive in a realistic and lumpy halo for a Hubble time. This suggests that upcoming stellar surveys will likely uncover more thin streams which may contain density gaps that have been shown to be promising probes for dark matter substructures.

Published
2016

21. The Gaia-ESO Survey: New constraints on the Galactic disc velocity dispersion and its chemical dependencies

Author

Jack Lewis, A. Hourihane, Sofia Randich, Karin Lind, Paula Jofre, Ivan Minchev, E. Franciosini, S. Mikolaitis, Gerard Gilmore, R. F. G. Wyse, Laura Magrini, M. T. Costado, G. G. Sacco, L. Morbidelli, Gregory R. Ruchti, Vanessa Hill, Cristina Chiappini, P. de Laverny, Clare Worley, Alejandra Recio-Blanco, Elena Pancino, Carmela Lardo, Sofia Feltzing, Thomas Bensby, Georges Kordopatis, Ettore Flaccomio, Guillaume Guiglion, Simone Zaggia, Amelia Bayo, Sergey E. Koposov, Guiglion G., Recio-Blanco A., De Laverny P., Kordopatis G., Hill V., Mikolaitis S., Minchev I., Chiappini C., Wyse R.F.G., Gilmore G., Randich S., Feltzing S., Bensby T., Flaccomio E., Koposov S.E., Pancino E., Bayo A., Costado M.T., Franciosini E., Hourihane A., Jofre P., Lardo C., Lewis J., Lind K., Magrini L., Morbidelli L., Sacco G.G., Ruchti G., Worley C.C., and Zaggia S.

Subjects
010504 meteorology & atmospheric sciences, Metallicity, Milky Way, astro-ph.GA, FOS: Physical sciences, Kinematics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Galaxy: disk, Astronomi, astrofysik och kosmologi, 0103 physical sciences, stellar content [Galaxy], Astronomy, Astrophysics and Cosmology, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Spectrograph, QC, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, QB, Physics, Galaxy: stellar content, Turbulence, Stars: abundances, Velocity dispersion, abundances [Galaxy], Astronomy and Astrophysics, kinematics and dynamics [Galaxy], Astrophysics - Astrophysics of Galaxies, abundances [stars], Galaxy: abundance, Stars, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Galaxy: kinematics and dynamic, Astrophysics::Earth and Planetary Astrophysics, Data release, disk [Galaxy]
Abstract

Understanding the history and the evolution of the Milky Way disc is one of the main goals of modern astrophysics. We study the velocity dispersion behaviour of Galactic disc stars as a function of the [Mg/Fe] ratio, which can be used as a proxy of relative age. This key relation is essential to constrain the formation mechanisms of the disc stellar populations as well as the cooling processes. We used the recommended parameters and chemical abundances of 7800 FGK Milky Way field stars from the second internal data release of the Gaia-ESO Survey. These stars were observed with the GIRAFFE spectrograph, and cover a large spatial volume (6+0.2dex. First, the velocity dispersion increases with [Mg/Fe] at all [Fe/H] ratios for the thin-disc stars, and then it decreases for the thick-disc at the highest [Mg/Fe] abundances. Similar trends are observed within the errors for the azimuthal velocity dispersion, while a continuous increase with [Mg/Fe] is observed for the vertical velocity dispersion. The velocity dispersion decrease agrees with previous measurements of the RAVE survey, although it is observed here for a greater metallicity interval and a larger spatial volume. We confirm the existence of [Mg/Fe]-rich thick-disc stars with cool kinematics in the generally turbulent context of the primitive Galactic disc. This is discussed in the framework of the different disc formation scenarios., Comment: 14 pages, 13 figures, A&A accepted

Published
2015

22. Simulating tidal streams in a high-resolution dark matter halo

Abstract

We simulate tidal streams in the presence and absence of substructures inside the zero-redshift snapshot of the Via Lactea II (VL-2) simulation. A halo finder is used to remove and isolate the subhalos found inside the high-resolution dark matter halo of VL-2, and the potentials for both the main halo and all the subhalos are constructed individually using the self-consistent field method. This allows us to make direct comparison of tidal streams between a smooth halo and a lumpy halo without assuming idealized profiles or triaxial fits. We simulate the kinematics of a star cluster starting with the same orbital position but two different velocities. Although these two orbits are only moderately eccentric and have similar apo- and pericentric distances, we find that the two streams have very different morphologies. We conclude that our model of the potential of VL-2 can provide insights about tidal streams that have not been explored by previous studies using idealized or axisymmetric models.

Published
2015

23. TheGaia-ESO Survey: characterisation of the [α/Fe] sequences in the Milky Way discs

Author

G. Kordopatis, R. F. G. Wyse, G. Gilmore, A. Recio-Blanco, P. de Laverny, V. Hill, V. Adibekyan, U. Heiter, I. Minchev, B. Famaey, T. Bensby, S. Feltzing, G. Guiglion, A. J. Korn, Š. Mikolaitis, M. Schultheis, A. Vallenari, A. Bayo, G. Carraro, E. Flaccomio, E. Franciosini, A. Hourihane, P. Jofré, S. E. Koposov, C. Lardo, J. Lewis, K. Lind, L. Magrini, L. Morbidelli, E. Pancino, S. Randich, G. G. Sacco, C. C. Worley, S. Zaggia, Kordopatis G., Wyse R.F.G., Gilmore G., Recio-Blanco A., De Laverny P., Hill V., Adibekyan V., Heiter U., Minchev I., Famaey B., Bensby T., Feltzing S., Guiglion G., Korn A.J., Mikolaitis S., Schultheis M., Vallenari A., Bayo A., Carraro G., Flaccomio E., Franciosini E., Hourihane A., Jofre P., Koposov S.E., Lardo C., Lewis J., Lind K., Magrini L., Morbidelli L., Pancino E., Randich S., Sacco G.G., Worley C.C., and Zaggia S.

Subjects
astro-ph.GA, Milky Way, Metallicity, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, evolution [Galaxy], Galaxy: disk, Astronomi, astrofysik och kosmologi, 0103 physical sciences, stellar content [Galaxy], Astronomy, Astrophysics and Cosmology, 10. No inequality, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Galaxy: evolution, Physics, Galaxy: stellar content, 010308 nuclear & particles physics, Turbulence, Stars: abundances, abundances [Galaxy], Astronomy and Astrophysics, kinematics and dynamics [Galaxy], Thin disc, Astrophysics - Astrophysics of Galaxies, Galaxy, abundances [stars], Galaxy: abundance, Stars, Distribution function, Space and Planetary Science, Galaxy: abundances, Galaxy: kinematics and dynamics, Astrophysics of Galaxies (astro-ph.GA), Galaxy: kinematics and dynamic, Astrophysics::Earth and Planetary Astrophysics, disk [Galaxy], Double sequence
Abstract

We investigate, using the Gaia-ESO Survey internal Data-Release 2, the properties of the double sequence of the Milky Way discs (defined chemically as the high-alpha and low-alpha populations), and discuss their compatibility with discs defined by other means such as metallicity, kinematics or positions. This investigation uses two different approaches: in velocity space for stars located in the extended Solar neighbourhood, and in chemical space for stars at different ranges of Galactocentric radii and heights from the plane. The separation we find in velocity space allows us to investigate, in a novel manner, the extent in metallicity of each of the two sequences, identifying them with the two discs, without making any assumption about the shape of their metallicity distribution functions. Then, using the separation in chemical space, we characterise the spatial variation of the slopes of the [alpha/Fe] - [Fe/H] sequences for the thick and thin discs and the way in which the relative proportions of the two discs change across the Galaxy. We find that the thick disc (high-alpha sequence), extends up to [Fe/H]~ +0.2 and the thin disc (low-alpha sequence), at least down to [Fe/H]~ -0.8. Radial and vertical gradients in alpha-abundances are found for the thin disc, with mild spatial variations in its [alpha/Fe] - [Fe/H] paths, whereas for the thick disc we do not detect any such spatial variations. The small variations in the spatial [alpha/Fe] - [Fe/H] paths of the thin disc do not allow us to distinguish between formation models of this structure. On the other hand, the lack of radial gradients and [alpha/Fe] - [Fe/H] variations for the thick disc indicate that the mechanism responsible for the mixing of the metals in the young Galaxy (e.g. radial stellar migration or turbulent gaseous disc) was more efficient before the (present) thin disc started forming., 21 pages, 18 figures, accepted for publication in Astronomy & Astrophysics

Published
2015

24. Inside out and upside down: Tracing the assembly of a simulated disk galaxy using mono-age stellar populations

Abstract

We analyze the present day structure and assembly history of a high-resolution hydrodynamic simulation of the formation of a Milky-Way-(MW)-like disk galaxy, from the "Eris" simulation suite, dissecting it into cohorts of stars formed at different epochs of cosmic history. At z = 0, stars with t form < 2 Gyr mainly occupy the stellar spheroid, with the oldest (earliest forming) stars having more centrally concentrated profiles. The younger age cohorts populate disks of progressively longer radial scale lengths and shorter vertical scale heights. At a given radius, the vertical density profiles and velocity dispersions of stars vary smoothly as a function of age, and the superposition of old, vertically extended and young, vertically compact cohorts gives rise to a double-exponential profile like that observed in the MW. Turning to formation history, we find that the trends of spatial structure and kinematics with stellar age are largely imprinted at birth, or immediately thereafter. Stars that form during the active merger phase at z > 3 are quickly scattered into rounded, kinematically hot configurations. The oldest disk cohorts form in structures that are radially compact and relatively thick, while subsequent cohorts form in progressively larger, thinner, colder configurations from gas with increasing levels of rotational support. The disk thus forms "inside out" in a radial sense and "upside down" in a vertical sense. Secular heating and radial migration influence the final state of each age cohort, but the changes they produce are small compared to the trends established at formation. The predicted correlations of stellar age with spatial and kinematic structure are in good qualitative agreement with the correlations observed for mono-abundance stellar populations in the MW.

Published
2013

25. Hypervelocity stars and the environment of Sgr A*

Abstract

Hypervelocity stars (HVSs) are a natural consequence of the presence of a massive nuclear black hole (Sgr A*) in the Galactic Centre. Here we use the Brown et al. sample of unbound and bound HVSs together with numerical simulations of the propagation of HVSs in the Milky Way halo to constrain three plausible ejection mechanisms: (i) the scattering of stars bound to Sgr A* by an in-spiralling intermediate-mass black hole (IMBH); (ii) the disruption of stellar binaries in the tidal field of Sgr A*; and (iii) the two-body scattering of stars off a cluster of stellar-mass black holes orbiting Sgr A*. We compare the predicted radial and velocity distributions of HVSs with the limited-statistics data set currently available, and show that the IMBH model appears to produce a spectrum of ejection velocities that is too flat. Future astrometric and deep wide-field surveys of HVSs should shed unambiguous light on the stellar ejection mechanism and probe the Milky Way potential on scales as large as 200 kpc.

Published
2007

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