Migration and Mixing in the Galactic Disc from Encounters between Sagittarius and the Milky Way

Abstract

Stars born on near-circular orbits in spiral galaxies can subsequently migrate to different orbits due to interactions with non-axisymmetric disturbances within the disc such as bars or spiral arms. This paper extends the study of migration to examine the role of external influences using the example of the interaction of the Sagittarius dwarf galaxy (Sgr) with the Milky Way (MW). We first make impulse approximation estimates to characterize the influence of Sgr disc passages. The tidal forcing from Sgr can produce changes in both guiding radius ($\Delta R_g$) and orbital eccentricity, as quantified by the maximum radial excursion, $\Delta R_{\max }$. These changes follow a quadrupole-like pattern across the face of the disc, with amplitude increasing with Galactocentric radius. We next examine a collisionless N-body simulation of a Sgr-like satellite interacting with a MW-like galaxy and find that Sgr's influence in the outer disc dominates over the secular evolution of orbits between disc passages. Finally, we use the same simulation to explore possible observable signatures of Sgr-induced migration by painting the simulation with different age stellar populations. We find that following Sgr disc passages, the migration it induces manifests within an annulus as an approximate quadrupole in azimuthal metallicity variations (${\delta }_{[Fe/H]}$), along with systematic variations in orbital eccentricity, $\Delta R_{\max }$. These systematic variations can persist for several rotational periods. We conclude that this combination of signatures may be used to distinguish between the different migration mechanisms shaping the chemical abundance patterns of the Milky Way's thin disc.

arXiv comment17 pages, 13 figures, submitted to MNRAS

References in corpus (63)

• The cosmological simulation code GADGET-2
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• The New Galaxy: Signatures of its Formation
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: I. Morphology of the Sagittarius Core and Tidal Arms
• Radial Mixing in Galactic Discs
• Co-formation of the Galactic disc and the stellar halo
• Chemical Cartography with APOGEE: Metallicity Distribution Functions and the Chemical Structure of the Milky Way Disk
• AGAMA: Action-based galaxy modelling architecture
• The Sagittarius Dwarf Galaxy: a Model for Evolution in a Triaxial Milky Way Halo
• A dynamically young and perturbed Milky Way disk
• Riding the Spiral Waves: Implications of Stellar Migration for the Properties of Galactic Disks
• Chemodynamical evolution of the Milky Way disk I: The solar vicinity
• A New Mechanism for Radial Migration in Galactic Disks: Spiral-Bar Resonance Overlap
• Secular Evolution in Disk Galaxies
• Tango for three: Sagittarius, LMC, and the Milky Way
• The Sagittarius impact as an architect of spirality and outer rings in the Milky Way
• The Influence of Sagittarius and the Large Magellanic Cloud on the Milky Way Galaxy
• Vertical density waves in the Milky Way disc induced by the Sagittarius Dwarf Galaxy
• Life in the fast lane: a direct view of the dynamics, formation, and evolution of the Milky Way's bar
• Radial migration in galactic disks caused by resonance overlap of multiple patterns: Self-consistent simulations
• Evolution of Galactic Discs: Multiple Patterns, Radial Migration and Disc Outskirts
• Estimating stellar birth radii and the time evolution of the Milky Way's ISM metallicity gradient
• The age-metallicity structure of the Milky Way disk
• Radial Migration in Disk Galaxies I: Transient Spiral Structure and Dynamics
• Measuring Radial Orbit Migration in the Milky Way Disk
• Signatures of radial migration in barred galaxies: Azimuthal variations in the metallicity distribution of old stars
• Radial mixing in the outer Milky Way disk caused by an orbiting satellite
• Response of the Milky Way's disc to the Large Magellanic Cloud in a first infall scenario
• Radial Mixing in Galactic Disks: The Effects of Disk Structure and Satellite Bombardment
• The origin of the Gaia phase-plane spiral
• The Lazy Giants: APOGEE Abundances Reveal Low Star Formation Efficiencies in the Magellanic Clouds
• A review of action estimation methods for galactic dynamics
• Galactic seismology: the evolving "phase spiral" after the Sagittarius dwarf impact
• The last breath of the Sagittarius dSph
• Spiral-induced velocity and metallicity patterns in a cosmological zoom simulation of a Milky Way-sized galaxy
• The Inside-out Growth of the Galactic Disk
• Keeping it Cool: Much Orbit Migration, yet Little Heating, in the Galactic Disk
• A Tail of Two Populations: Chemo-dynamics of the Sagittarius Stream and Implications for its Original Mass
• Stellar diffusion in barred spiral galaxies
• Extended distribution functions for our Galaxy
• A new stellar chemo-kinematic relation reveals the merger history of the Milky Way disc
• Imprints of radial migration on the Milky Way's metallicity distribution functions
• In the Galactic disk, stellar [Fe/H] and age predict orbits and precise [X/Fe]
• Spatial variations in the Milky Way disc metallicity-age relation
• Chaos caused by resonance overlap in the solar neighborhood -- Spiral structure at the Bar's 2:1 outer Lindblad resonance
• A Recent Lindblad Resonance in the Solar Neighbourhood
• Stellar migrations and metal flows -- Chemical evolution of the thin disc of a simulated Milky Way analogous galaxy
• Evolution of the Milky Way with radial motions of stars and gas II. The evolution of abundance profiles from H to Ni
• Measuring the mixing scale of the ISM within nearby spiral galaxies
• Metallicity Structure in the Milky Way Disk Revealed by Galactic HII Regions
• On the Origin of Dynamically Cold Rings Around the Milky Way
• Stellar Abundance Maps of the Milky Way Disk
• The Gaia-ESO Survey: New constraints on the Galactic disc velocity dispersion and its chemical dependencies
• Chemo-dynamical properties of the Anticenter Stream: a surviving disc fossil from a past satellite interaction
• Evidence for coupling between the Sagittarius dwarf galaxy and the Milky Way warp
• Abundances in the Milky Way across five nucleosynthetic channels from 4 million LAMOST stars
• Phase Wrapping of Epicyclic Perturbations in the Wobbly Galaxy
• The Gaia-ESO Survey: Churning through the Milky Way
• An estimate of the time variation of the abundance gradient from planetary nebulae II. Comparison with open clusters, cepheids and young objects
• Measuring the vertical response of the Galactic disc to an infalling satellite
• Revealing the spiral arms through radial migration and the shape of the Metallicity Distribution Function
• The Implications of Local Fluctuations in the Galactic Midplane for Dynamical Analysis in the Gaia Era
• Turning Points in the Age-Metallicity Relations -- Created by Late Satellite Infall and Enhanced by Radial Migration

Cited by in corpus (15)

• Spectroscopic age estimates for APOGEE red-giant stars: Precise spatial and kinematic trends with age in the Galactic disc
• Unveiling the time evolution of chemical abundances across the Milky Way disk with APOGEE
• Chemical Cartography with LAMOST and Gaia Reveal Azimuthal and Spiral Structure in the Galactic Disk
• Mapping the anisotropic Galactic stellar halo with Blue Horizontal Branch stars
• Observational Constraints of Radial Migration in the Galactic Disc Driven by the Slowing Bar
• The metallicity distribution in the core of the Sagittarus dwarf spheroidal: minimising the metallicity biases
• Empirical derivation of the metallicity evolution with time and radius using TNG50 Milky Way/Andromeda analogues
• The Non-Axisymmetric Influence: Radius and Angle-Dependent Trends in a Barred Galaxy
• Constraints on the history of Galactic spiral arms revealed by Gaia GSP-Spec alpha-elements
• Effects of secular growth and mergers on the evolution of metallicity gradients and azimuthal variations in a Milky Way-like galaxy
• Probing the origins. I. Generalised Additive Model inference of birth radii for Milky Way stars in the solar vicinity
• The Milky Way in context: The formation of galactic discs and chemical sequences from a cosmological perspective
• Metal-rich stellar counterpart of the Radcliffe Wave and the 3D chemical footprints of the Milky Way spiral arms
• Tidally-induced radial migration waves in LMC-like galaxies
• Evolution and star formation history of NGC300 from a chemical evolution model with radial gas inflows