The Milky Way Revealed by Variable Stars I: Sample Selection of RR Lyrae stars, and Evidence for the Merger History

Abstract

In order to study the Milky Way, RR Lyrae (RRL) variable stars identified by Gaia, ASAS-SN and ZTF sky survey projects have been analyzed as tracers in this work. Photometric and spectroscopic information of 3417 RRLs including proper motions, radial velocity and metallcity are obtained from observational data of Gaia, LAMOST, GALAH, APOGEE and RAVE. Precise distances of RRLs with typical uncertainties less than 3% are derived by using a recent comprehensive period-luminosity-metallicity relation. Our results from kinematical and chemical analysis provide important clues for the assembly history of the Milky Way, especially for the Gaia-Sausage ancient merger. The kinematical and chemical trends found in this work are consistent with that of recent simulations which indicated that the Gaia-Sausage merger is the dual origin of the Galactic thick disc and halo. As recent similar works have found, the halo RRLs sample in this work contains a subset of radially biased orbits besides a more isotropic component. This higher orbital anisotropy component amounts to $\beta \simeq 0.8$, and it contributes between 42% and 83% of the halo RRLs at $4<R(\mathrm{kpc})<20$.

arXiv comment31 pages, 11 figures; accepted for publication in ApJS

References in corpus (107)

• emcee: The MCMC Hammer
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Gaia mission
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• Trigonometric Parallaxes of High Mass Star Forming Regions: the Structure and Kinematics of the Milky Way
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• Tracing Galaxy Formation with Stellar Halos I: Methods
• Co-formation of the Galactic disc and the stellar halo
• Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole
• The Field of Streams: Sagittarius and its Siblings
• The GALAH Survey: Scientific Motivation
• The Ghost of Sagittarius and Lumps in the Halo of the Milky Way
• Kinematics of Metal-Poor Stars in the Galaxy. III. Formation of the Stellar Halo and Thick Disk as Revealed from a Large Sample of Non-Kinematically Selected Stars
• Chemical Cartography with APOGEE: Metallicity Distribution Functions and the Chemical Structure of the Milky Way Disk
• Debris streams in the solar neighbourhood as relicts from the formation of the Milky Way
• Reddening and Extinction Toward the Galactic Bulge from OGLE-III: The Inner Milky Way's Rv ~ 2.5 Extinction Curve
• The age structure of stellar populations in the solar vicinity. Clues of a two-phase formation history of the Milky Way disk
• Structure and Kinematics of the Stellar Halos and Thick Disks of the Milky Way Based on Calibration Stars from SDSS DR7
• Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. V. Evidence for a wide age distribution and a complex MDF
• The Catalina Surveys Periodic Variable Star Catalog
• The spatial structure of mono-abundance sub-populations of the Milky Way disk
• The ASAS-SN Catalog of Variable Stars I: The Serendipitous Survey
• Mapping the Three-Dimensional Density of the Galactic Bulge with VVV Red Clump Stars
• The RAdial Velocity Experiment (RAVE): Fourth data release
• Identification of A-colored Stars and Structure in the Halo of the Milky Way from SDSS Commissioning Data
• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• The GALAH Survey: Second Data Release
• The Fifteenth Data Release of the Sloan Digital Sky Surveys: First Release of MaNGA Derived Quantities, Data Visualization Tools and Stellar Library
• On the mass-to-light ratio of the local Galactic disc and the optical luminosity of the Galaxy
• The Metal Content of Bulge Field Stars from FLAMES-GIRAFFE Spectra. I. Stellar parameters and Iron Abundances
• Detection of a 63 Degree Cold Stellar Stream in the Sloan Digital Sky Survey
• ARGOS III: Stellar Populations in the Galactic Bulge of the Milky Way
• The Zwicky Transient Facility Catalog of Periodic Variable Stars
• The Biggest Splash
• Substructure revealed by RR Lyraes in SDSS Stripe 82
• The birth of the Milky Way as uncovered by accurate stellar ages with Gaia
• The Milky Way's Stellar Disk
• Vertical distribution of Galactic disk stars I - Kinematics and metallicity
• Multiple retrograde substructures in the Galactic halo: A shattered view of Galactic history
• The QUEST RR Lyrae Survey: Confirmation of the Clump at 50 kpc and Other Over-Densities in the Outer Halo
• The GALAH survey and Gaia DR2: dissecting the stellar disc's phase space by age, action, chemistry and location
• Chemodynamics of the Milky Way. I. The first year of APOGEE data
• The Sausage Globular Clusters
• Chemodynamical history of the Galactic Bulge
• Tracing chemical evolution over the extent of the Milky Way's Disk with APOGEE Red Clump Stars
• Gaia reveals a metal-rich in-situ component of the local stellar halo
• The hidden giant: discovery of an enormous Galactic dwarf satellite in Gaia DR2
• One large blob and many streams frosting the nearby stellar halo in Gaia DR2
• The origin of the split red clump in the Galactic bulge of the Milky Way
• Dark matter local density determination: recent observations and future prospects
• Deciphering the 3D structure of the old Galactic bulge from the OGLE RR Lyrae stars
• Chemodynamics of barred galaxies in cosmological simulations: On the Milky Way's quiescent merger history and in-situ bulge
• Mapping the X-Shaped Milky Way Bulge
• ARGOS II: The Galactic Bulge Survey
• The shape of the Galactic halo with $Gaia$ DR2 RR Lyrae. Anatomy of an ancient major merger
• Apocenter Pile-Up: Origin of the Stellar Halo Density Break
• Piercing the Milky Way: an all-sky view of the Orphan Stream
• Sausage & Mash: The dual origin of the Galactic thick disc and halo from the gas-rich Gaia-Enceladus-Sausage merger
• A Synoptic Map of Halo Substructures from the Pan-STARRS1 3π Survey
• A box full of chocolates: The rich structure of the nearby stellar halo revealed by Gaia and RAVE
• Stellar haloes in Milky-Way mass galaxies: From the inner to the outer haloes
• Weighing the stellar constituents of the Galactic halo with APOGEE red giant stars
• Inferred Evidence For Dark Matter Kinematic Substructure with SDSS-Gaia
• Chemo-kinematics of the $Gaia$ RR Lyrae: the halo and the disc
• The Gravitational Force Field of the Galaxy Measured From the Kinematics of RR Lyrae in Gaia
• Before the Bar: Kinematic Detection of A Spheroidal Metal-Poor Bulge Component
• The Halo's Ancient Metal-Rich Progenitor Revealed with BHB Stars
• Understanding inverse metallicity gradients in galactic discs as a consequence of inside-out formation
• Kinematics of the Outer Stellar Halo
• Fashionably Late? Building up the Milky Way's Inner Halo
• Fourteen candidate RR Lyrae star streams in the inner Galaxy
• The first all-sky view of the Milky Way stellar halo with Gaia+2MASS RR Lyrae
• The slight spin of the old stellar halo
• The Optical Gravitational Lensing Experiment: Analysis of the bulge RR Lyrae population from the OGLE-III data
• Kinematics of the local disk from the RAVE survey and the Gaia first data release
• SPCANet: Stellar Parameters and Chemical Abundances Network for LAMOST-II Medium Resolution Survey
• The Rotation Curve, Mass Distribution and Dark Matter Content of the Milky Way from Classical Cepheids
• Common origin for Hercules-Aquila and Virgo Clouds in Gaia DR2
• Tracing the Orphan Stream to 55 kpc with RR Lyrae Stars
• On a new theoretical framework for RR Lyrae stars II: Mid--Infrared Period--Luminosity--Metallicity Relations
• The Profile of the Galactic Halo from Pan-STARRS1 3$\pi$ RR Lyrae
• A new class of fossil fragments from the hierarchical assembly of the Galactic bulge
• The Galactic Thick Disc density profile traced with RR Lyrae stars
• A Probabilistic Approach to Fitting Period-Luminosity Relations and Validating Gaia Parallaxes
• Evidence for Galactic disc RR~Lyrae stars in the Solar neighbourhood
• Unmixing the Galactic Halo with RR Lyrae tagging
• The X-Shaped Milky Way Bulge in OGLE-III Photometry and in N-Body Models
• Update on the Nature of Virgo Overdensity
• Multiwavelength Characteristics of Period-Luminosity Relations
• Yule-Simpson's paradox in Galactic Archaeology
• A Near-infrared RR Lyrae census along the southern Galactic plane: the Milky Way's stellar fossil brought to light
• Local RR Lyrae Stars: native and alien
• Constraints on stellar rotation from the evolution of Sr and Ba in the Galactic halo
• The Milky Way's circular velocity curve and its constraint on the Galactic mass with RR Lyrae stars
• What to expect from dynamical modelling of galactic haloes II: the spherical Jeans equation
• The Rotation-Metallicity Relation for the Galactic Disk as Measured in the Gaia DR1 TGAS and APOGEE Data
• Weighing the Galactic disk in sub-regions of the solar neighbourhood using Gaia DR2
• On the Oosterhoff dichotomy in the Galactic bulge: I. spatial distribution
• Masses of RR Lyrae Stars with Different Chemical Abundances in the Galactic Field
• Metallicity Gradient of the Thick Disc Progenitor at High Redshift
• The RR Lyrae projected density distribution from the Galactic centre to the halo
• The Density Profile and Kinematics of the Milky Way with RR Lyrae Stars
• Equilibrium axisymmetric halo model for the Milky Way and its implications for direct and indirect DM searches
• Study of the Galactic Rotation Based on Masers and Radio Stars with VLBI Measurements of Their Parallaxes
• Fading Features Found in the Kinematics of the Far-Reaching Milky Way Stellar Halo
• Ergodic Considerations in the Gravitational Potential of the Milky Way

Cited by in corpus (2)

• RR Lyrae From Binary Evolution: Abundant, Young and Metal-Rich
• Influence of the Gaia-Sausage-Enceladus on the density shape of the Galactic stellar halo revealed by halo K giants from the LAMOST survey