The Photo-Astrometric Vertical Tracer Density of the Milky Way II: Results from Gaia

Abstract

We use Gaia photometry and astrometry to estimate the vertical spatial structure of the Milky Way at the Solar radius, formally accounting for sample incompleteness (the selection function) and parallax measurement uncertainty. Our results show impressive precision demonstrating the power of the Gaia data. However, systematic errors dominate the parameter value uncertainties. We thoroughly test and quantify the impacts of all systematic uncertainties. The vertical tracer density is modelled as a sum of two exponential profiles for the thin and thick discs, together with a spherically symmetric power-law for the stellar halo. We constrain the thin disc scale height as $h_{\mathrm{Tn}}=260\pm 3(\mathrm{stat})\pm 26\mathrm{pc}(\mathrm{sys})$ and thick disc $h_{\mathrm{Tk}}=693\pm 7(\mathrm{stat})\pm 121\mathrm{pc}(\mathrm{sys})$. For the halo, we obtain a power law profile with $n_{\mathrm{H}}=3.543\pm 0.023(\mathrm{stat})\pm 0.259(\mathrm{sys})$. We infer a local stellar mass density for non-compact object stars of ${\rho }_{\mathrm{local}}^{\ast }=3.66\pm 0.03(\mathrm{stat})\pm 0.52\times 10^{-2}{\mathrm{M}}_{\odot }/{\mathrm{pc}}^3(\mathrm{sys})$ and surface density of ${\Sigma }_{\mathrm{local}}^{\ast }=23.17\pm 0.08(\mathrm{stat})\pm 2.43{\mathrm{M}}_{\odot }/{\mathrm{pc}}^2(\mathrm{sys})$. We find asymmetries above and below the disc with longer disc scale heights in the north but a flatter halo in the south at the $\lesssim 10$ per cent level.

arXiv commentResubmitted to MNRAS after first referee review

References in corpus (70)

• emcee: The MCMC Hammer
• On the variation of the Initial Mass Function
• The Gaia mission
• The observed properties of dwarf galaxies in and around the Local Group
• The Sloan Digital Sky Survey Photometric Camera
• Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
• The Milky Way Tomography with SDSS: I. Stellar Number Density Distribution
• A 3D Dust Map Based on Gaia, Pan-STARRS 1 and 2MASS
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• Gaia Early Data Release 3: The astrometric solution
• Co-formation of the Galactic disc and the stellar halo
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• The Field of Streams: Sagittarius and its Siblings
• Gaia Early Data Release 3: Photometric content and validation
• Cosmic Distances Calibrated to 1% Precision with Gaia EDR3 Parallaxes and Hubble Space Telescope Photometry of 75 Milky Way Cepheids Confirm Tension with LambdaCDM
• Gaia Data Release 2: Photometric content and validation
• Gaia Data Release 2: using Gaia parallaxes
• A dynamically young and perturbed Milky Way disk
• A million binaries from Gaia eDR3: sample selection and validation of Gaia parallax uncertainties
• The Local Dark Matter Density
• The accretion origin of the Milky Way's stellar halo
• Vertical waves in the solar neighbourhood in Gaia DR2
• Unresolved stellar companions with Gaia DR2 astrometry
• Identification of A-colored Stars and Structure in the Halo of the Milky Way from SDSS Commissioning Data
• The photometric structure of the inner Galaxy
• unWISE: unblurred coadds of the WISE imaging
• On the mass-to-light ratio of the local Galactic disc and the optical luminosity of the Galaxy
• Gaia Early Data Release 3: The Gaia Catalogue of Nearby Stars
• Galactoseismology: Discovery of Vertical Waves in the Galactic Disk
• The Milky Way stellar halo out to 40 kpc : Squashed, broken but smooth
• The Biggest Splash
• Tango for three: Sagittarius, LMC, and the Milky Way
• The Milky Way has no thick disk
• Parallax Systematics and Photocenter Motions of Benchmark Eclipsing Binaries in Gaia EDR3
• Substructure revealed by RR Lyraes in SDSS Stripe 82
• Mapping the stellar structure of the Milky Way thick disk and halo using SEGUE photometry
• The age-metallicity structure of the Milky Way disk
• Reconstructing the star formation history of the Milky Way disc(s) from chemical abundances
• Kinematics of SDSS subdwarfs: Structure and substructure of the Milky Way halo
• Disk M Dwarf Luminosity Function From HST Star Counts
• The total stellar halo mass of the Milky Way
• The shape of the Galactic halo with $Gaia$ DR2 RR Lyrae. Anatomy of an ancient major merger
• Sausage & Mash: The dual origin of the Galactic thick disc and halo from the gas-rich Gaia-Enceladus-Sausage merger
• Clouds, Streams and Bridges. Redrawing the blueprint of the Magellanic System with Gaia DR1
• Binary deviations from single object astrometry
• Displacement of the Sun from the Galactic Plane
• Touching The Void: A Striking Drop in Stellar Halo Density Beyond 50 kpc
• The first all-sky view of the Milky Way stellar halo with Gaia+2MASS RR Lyrae
• Catalogues of Active Galactic Nuclei From Gaia and unWISE Data
• Completeness of the Gaia-verse II: what are the odds that a star is missing from Gaia DR2?
• Aurigaia: mock Gaia DR2 stellar catalogues from the Auriga cosmological simulations
• Quasar and galaxy classification in Gaia Data Release 2
• The Parallax Zero-Point of Gaia Early Data Release 3 from LAMOST Primary Red Clump Stars
• The Profile of the Galactic Halo from Pan-STARRS1 3$\pi$ RR Lyrae
• Gaia EDR3 Parallax Zero-point Offset based on W Ursae Majoris-type Eclipsing Binaries
• A-type stars in the Canada-France Imaging Survey I. The stellar halo of the Milky Way traced to large radius by blue horizontal branch stars
• The Galactic Thick Disc density profile traced with RR Lyrae stars
• Spatial distribution and galactic model parameters of cataclysmic variables
• Galactic longitude dependent Galactic model parameters
• Completeness of the Gaia-verse I: when and where were Gaia's eyes on the sky during DR2?
• The Outer Halo of the Milky Way as Probed by RR Lyr Variables from the Palomar Transient Facility
• The stellar halo of the Milky Way traced by blue horizontal-branch stars in the Subaru Hyper Suprime-Cam Survey
• Completeness of the Gaia-verse IV: The Astrometry Spread Function of Gaia DR2
• The dynamical matter density in the solar neighbourhood inferred from Gaia DR1
• Galactic model parameters for field giants separated from field dwarfs by their 2MASS and V apparent magnitudes
• The Milky Way's stellar halo - lumpy or triaxial?
• The Tilt of the Local Velocity Ellipsoid as Seen by Gaia
• Completeness of the Gaia-verse III: using hidden states to infer gaps, detection efficiencies and the scanning law from the DR2 light curves
• A Bayesian Approach to the Vertical Structure of the Disk of the Milky Way
• seestar: Selection functions for spectroscopic surveys of the Milky Way

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• Self-consistent models of our Galaxy
• On the origin of the Galactic thin and thick discs, their abundance gradients and the diagnostic potential of their abundance ratios
• Milky Way thin and thick disk kinematics with GAIA EDR3 and RAVE DR5
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• Interstellar Bow Shocks around Fast Stars Passing through the Local Interstellar Medium
• Natal kicks of compact objects
• Topography of the Young Galactic Disk: Spatial and Kinematic Patterns of the Clustered Star Formation in the Solar Neighborhood
• Modeling the Mass Distribution and Gravitational Potential of Nearby Disk Galaxies: Implications for the ISM Dynamical Equilibrium
• A new method to retrieve the star formation history from white dwarf luminosity functions -- an application to the Gaia catalogue of nearby stars
• Validation of the Bond et al. (2010) SDSS-derived kinematic models for the Milky Way's disk and halo stars with Gaia Data Release 3 proper motion and radial velocity data