@article{53bf7580e33843c2b8c6a8ff1e2f9d4c,
title = "Dynamical heating across the Milky Way disc using APOGEE and Gaia",
abstract = "The kinematics of the Milky Way disc as a function of age are well measured at the solar radius, but have not been studied over a wider range of Galactocentric radii. Here, we measure the kinematics of mono-age, mono-[Fe/H] populations in the low and high [α/Fe] discs between 4 ≲ R ≲ 13 kpc and |z| ≲ 2 kpc using 65 719 stars in common between APOGEE DR14 and Gaia DR2 for which we estimate ages using a Bayesian neural network model trained on asteroseismic ages. We determine the vertical and radial velocity dispersions, finding that the low and high [α/Fe] discs display markedly different age-velocity dispersion relations (AVRs) and shapes σz/σR. The high [α/Fe] disc has roughly flat AVRs and constant σz/σR = 0.64 ± 0.04, whereas the low [α/Fe] disc has large variations in this ratio that positively correlate with the mean orbital radius of the population at fixed age. The high [α/Fe] disc component's flat AVRs and constant σz/σR clearly indicate an entirely different heating history. Outer disc populations also have flatter radial AVRs than those in the inner disc, likely due to the waning effect of spiral arms. Our detailed measurements of AVRs and σz/σR across the disc indicate that low [α/Fe], inner disc (R ≲ 10 kpc) stellar populations are likely dynamically heated by both giant molecular clouds and spiral arms, while the observed trends for outer disc populations require a significant contribution from another heating mechanism such as satellite perturbations. We also find that outer disc populations have slightly positive mean vertical and radial velocities likely because they are part of the warped disc.",
keywords = "Galaxy: disc, Galaxy: evolution, Galaxy: formation, Galaxy: kinematics and dynamics, Galaxy: stellar content",
author = "{Ted Mackereth}, J. and Jo Bovy and Leung, {Henry W.} and Schiavon, {Ricardo P.} and Trick, {Wilma H.} and Chaplin, {William J.} and Katia Cunha and Feuillet, {Diane K.} and Majewski, {Steven R.} and Marie Martig and Andrea Miglio and David Nidever and Pinsonneault, {Marc H.} and Aguirre, {Victor Silva} and Jennifer Sobeck and Jamie Tayar and Gail Zasowski",
note = "Funding Information: The authors thank the anonymous referee for a useful report. We also thank Ivan Minchev, Jerry Sellwood, Chao Liu, and Michael Hayden for helpful discussions on the originally submitted manuscript. We also thank Leandro Silva and Martin Smith for highlighting necessary typographic corrections. JTM is funded by an 〈0: funding-source 〉〈0:funding-source 〉STFC〈/0:funding-source〉〈/0: funding-source〉 studentship, and is grateful for funding from the Royal Astronomical Society and the Dunlap Institute for Astronomy and Astrophysics at the University of Toronto and thanks them for their hospitality during an extended visit while preparing this work. JTM and AM acknowledge support from the ERC Consolidator Grant funding scheme (project ASTEROCHRONOMETRY, G.A. n. 772293). JB acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC), funding reference number RGPIN-2015-05235, and from an Alfred P. Sloan Fellowship. JT acknowledges that support for this work was provided by NASA through the NASA Hubble Fellowship grant #51424 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. This project was developed in part at the 2017 Heidelberg Gaia Sprint, hosted by the Max-Planck-Institut f{\"u}r Astronomie, Heidelberg, and the 2018 NYC Gaia Sprint, hosted by the Center for Computational Astrophysics of the Flatiron Institute in New York City. This research has used the cross-match service provided by CDS, Strasbourg. Analyses and plots presented in this article used iPython, and packages in the SciPy ecosystem (Jones et al. 2001; Hunter 2007; Perez & Granger 2007; van der Walt, Colbert & Varoquaux 2011). The study has used high performance computing facilities at Liverpool John Moores University, partly funded by the Royal Society and LJMU's Faculty of Engineering and Technology. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS web site is www.sdss.org. SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Brazilian Participation Group, the Carnegie Institution for Science, Carnegie Mellon University, the Chilean Participation Group, the French Participation Group, Harvard-Smithsonian Center for Astrophysics, Instituto de Astrof{\'i}sica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU) / University of Tokyo, the Korean Participation Group, Lawrence Berkeley National Laboratory, Leibniz Institut f{\"u}r Astrophysik Potsdam (AIP), Max-Planck-Institut f{\"u}r Astronomie (MPIA Heidelberg), Max-Planck-Institut f{\"u}r Astrophysik (MPA Garching), Max-Planck-Institut f{\"u}r Extraterrestrische Physik (MPE), National Astronomical Observatories of China, New Mexico State University, New York University, University of Notre Dame, Observat{\'a}rio Nacional / MCTI, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Aut{\'o}noma de M{\'e}xico, University of Arizona, University of Colorado Boulder, University of Oxford, University of Portsmouth, University of Utah, University of Virginia, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University. This work has used data from the European Space Agency (ESA) mission Gaia (http://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, http: //www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Funding Information: This research has used the cross-match service provided by CDS, Strasbourg. Analyses and plots presented in this article used iPython, and packages in the SciPy ecosystem (Jones et al. 2001; Hunter 2007; Perez & Granger 2007; van der Walt, Colbert & Varoquaux 2011). The study has used high performance computing facilities at Liverpool John Moores University, partly funded by the Royal Society and LJMU{\textquoteright}s Faculty of Engineering and Technology. Funding Information: The authors thank the anonymous referee for a useful report. We also thank Ivan Minchev, Jerry Sellwood, Chao Liu, and Michael Hayden for helpful discussions on the originally submitted manuscript. We also thank Leandro Silva and Martin Smith for highlighting necessary typographic corrections. JTM is funded by an 〈0: funding-source 〉〈0:funding-source 〉STFC〈/0:funding-source〉〈/0: funding-source〉 studentship, and is grateful for funding from the Royal Astronomical Society and the Dunlap Institute for Astronomy and Astrophysics at the University of Toronto and thanks them for their hospitality during an extended visit while preparing this work. JTM and AM acknowledge support from the ERC Consolidator Grant funding scheme (project ASTEROCHRONOMETRY, G.A. n. 772293). JB acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC), funding reference number RGPIN-2015-05235, and from an Alfred P. Sloan Fellowship. JT acknowledges that support for this work was provided by NASA through the NASA Hubble Fellowship grant #51424 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. This project was developed in part at the 2017 Heidelberg Gaia Sprint, hosted by the Max-Planck-Institut f{\"u}r Astronomie, Heidelberg, and the 2018 NYC Gaia Sprint, hosted by the Center for Computational Astrophysics of the Flatiron Institute in New York City. Funding Information: Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS web site is www.sdss.org. Publisher Copyright: {\textcopyright} 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society",
year = "2019",
month = oct,
day = "11",
doi = "10.1093/mnras/stz1521",
language = "English (US)",
volume = "489",
pages = "176--195",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "1",
}