Towards a fully consistent Milky Way disk model -- IV. The impact of Gaia DR2 and APOGEE

Abstract

We present an updated version of the semi-analytic Just-Jahreiß (JJ) model of the Galactic disk and constrain its parameters in the Solar neighbourhood. The new features of the JJ model include a simple two-component gaseous disk, a star-formation rate (SFR) function of the thick disk that has been extended in time, and a correlation between the kinematics of molecular gas and thin-disk populations. Here, we study the vertical number density profiles and W-velocity distributions determined from ~2 million local stars of the Gaia DR2. We also investigate an apparent Hess diagram of the Gaia stars selected in a conic volume towards the Galactic poles. Using a stellar evolution library, we synthesise stellar populations with a four-slope broken power-law initial mass function (IMF), the SFR, and an age-metallicity relation (AMR). The latter is consistently derived with the observed metallicity distribution of the local Red Clump (RC) giants from the APOGEE. Working within a Bayesian approach, we sample the posterior probability distribution in a multidimensional parameter space using the MCMC method. We find that the spatial distribution and motion of the Gaia stars imply two recent SF bursts centered at ages of ~0.5 Gyr and ~3 Gyr and characterised by a ~30% and ~55% SF enhancement, respectively, relative to a monotonously declining SFR continuum. The stellar populations associated with this SF excess are found to be dynamically hot for their age: they have W-velocity dispersions of ~12.5 km/s and ~26 km/s. The new JJ model is able to reproduce the local star counts with an accuracy of ~5 %. Using Gaia DR2 data, we self-consistently constrained 22 parameters of the updated JJ model. Our optimised model predicts two SF bursts within the last ~4 Gyr, which may point to recent episodes of gas infall.

29 pages, 16 figures, 4 tables. Accepted for publication in Astronomy&Astrophysics on December 1, 2020

References in corpus (28)

• The NumPy array: a structure for efficient numerical computation
• Modules for Experiments in Stellar Astrophysics (MESA)
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey
• Gaia Data Release 1: Astrometry - one billion positions, two million proper motions and parallaxes
• The Radial Velocity Experiment (RAVE): Fifth Data Release
• Present-day cosmic abundances. A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models
• The Local Dark Matter Density
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• On the mass-to-light ratio of the local Galactic disc and the optical luminosity of the Galaxy
• Clusters and mirages: cataloguing stellar aggregates in the Milky Way
• The APOGEE red-clump catalog: Precise distances, velocities, and high-resolution elemental abundances over a large area of the Milky Way's disk
• A catalog of newly identified star clusters in GAIA DR2
• The GALAH Survey: Observational Overview and Gaia DR1 companion
• Reconstructing the star formation history of the Milky Way disc(s) from chemical abundances
• Bending and Breathing Modes of the Galactic Disk
• Gaia DR2 reveals a star formation burst in the disc 2-3 Gyr ago
• Extended stellar systems in the solar neighborhood - II. Discovery of a nearby 120° stellar stream in Gaia DR2
• Recovering the star formation rate in the solar neighborhood
• Revisiting two local constraints of the Galactic chemical evolution
• Kinematics of the local disk from the RAVE survey and the Gaia first data release
• Quasar and galaxy classification in Gaia Data Release 2
• The Galactic spiral structure as revealed by O- and early B-type stars
• Code dependencies of pre-supernova evolution and nucleosynthesis in massive stars: Evolution to the end of core helium burning
• Towards a fully consistent Milky Way disc model - III. Constraining the initial mass function
• The origin of abundance gradients in the Milky Way: the predictions of different models
• Towards a fully consistent Milky Way disc model - II. The local disc model and SDSS data of the NGP region
• Another relic bulge globular cluster: ESO 456-SC38 (Djorgovski~2)

Cited by in corpus (5)

• The Galactic metallicity gradient shown by open clusters in the light of radial migration
• A self-consistent dynamical model of the Milky Way disc adjusted to Gaia data
• Global survey of star clusters in the Milky Way -- VII. Tidal parameters and mass function
• Arm Tangents and the spiral structure of the Milky Way ; the Age Gradient
• Towards a fully consistent Milky Way disk model V. The disk model for 4 $-$ 14 kpc