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.

Resubmitted to MNRAS after first referee review

References in corpus (33)

• The Gaia mission
• Gaia Early Data Release 3: The astrometric solution
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• 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
• The Local Dark Matter Density
• A million binaries from Gaia eDR3: sample selection and validation of Gaia parallax uncertainties
• The accretion origin of the Milky Way's stellar halo
• Unresolved stellar companions with Gaia DR2 astrometry
• 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
• Tango for three: Sagittarius, LMC, and the Milky Way
• Parallax Systematics and Photocenter Motions of Benchmark Eclipsing Binaries in Gaia EDR3
• The age-metallicity structure of the Milky Way disk
• Reconstructing the star formation history of the Milky Way disc(s) from chemical abundances
• The total stellar halo mass of the Milky Way
• 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
• Completeness of the Gaia-verse II: what are the odds that a star is missing from Gaia DR2?
• 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
• Gaia EDR3 Parallax Zero-point Offset based on W Ursae Majoris-type Eclipsing Binaries
• 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
• Completeness of the Gaia-verse III: using hidden states to infer gaps, detection efficiencies and the scanning law from the DR2 light curves

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• Modeling the Mass Distribution and Gravitational Potential of Nearby Disk Galaxies: Implications for the ISM Dynamical Equilibrium
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