Dynamically constraining the length of the Milky Way bar

Abstract

We present a novel method for constraining the length of the Galactic bar using 6D phase space information to directly integrate orbits. We define a pseudo-length for the Galactic bar, named $R_{Freq}$, based on the maximal extent of trapped bar orbits. We find the $R_{Freq}$ measured from orbits is consistent with the $R_{Freq}$ of the assumed potential only when the length of the bar and pattern speed of said potential is similar to the model from which the initial phase-space coordinates of the orbits are derived. Therefore, one can measure the model's or the Milky Way's bar length from 6D phase-space coordinates by determining which assumed potential leads to a self-consistent measured $R_{Freq}$. When we apply this method to $\approx$210,000 stars in APOGEE DR17 and $Gaia$ eDR3 data, we find a consistent result only for potential models with a dynamical bar length of $\approx$3.5 kpc. We find the Milky Way's trapped bar orbits extend out to only $\approx$3.5 kpc, but there is also an overdensity of stars at the end of the bar out to 4.8 kpc which could be related to an attached spiral arm. We also find that the measured orbital structure of the bar is strongly dependent on the properties of the assumed potential.

arXiv comment15 pages, 8 figures, 2 tables, accepted to MNRAS, comments welcome

References in corpus (87)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The 2.5 m Telescope of the Sloan Digital Sky Survey
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• galpy: A Python Library for Galactic Dynamics
• ASPCAP: The Apogee Stellar Parameter and Chemical Abundances Pipeline
• Reddening and Extinction Toward the Galactic Bulge from OGLE-III: The Inner Milky Way's Rv ~ 2.5 Extinction Curve
• Constraints from Dynamical Friction on the Dark Matter Content of Barred Galaxies
• AGAMA: Action-based galaxy modelling architecture
• Dynamics of Barred Galaxies
• A dynamically young and perturbed Milky Way disk
• The Effect of the Outer Lindblad Resonance of the Galactic Bar on the Local Stellar Velocity Distribution
• Morphology, photometry and kinematics of N-body bars. I Three models with different halo central concentrations
• The Data Reduction Pipeline for the Apache Point Observatory Galactic Evolution Experiment
• Evolution of Stellar Bars in Live Axisymmetric Halos: Recurrent Buckling and Secular Growth
• Mapping the Three-Dimensional Density of the Galactic Bulge with VVV Red Clump Stars
• A New Mechanism for Radial Migration in Galactic Disks: Spiral-Bar Resonance Overlap
• Dynamical modelling of the Galactic bulge and bar: the Milky Way's bar pattern speed, stellar, and dark matter mass distribution
• The Structure of the Milky Way's Bar Outside the Bulge
• Our Milky Way as a Pure-Disk Galaxy -- A Challenge for Galaxy Formation
• ARGOS III: Stellar Populations in the Galactic Bulge of the Milky Way
• Galaxy Zoo: Bars in Disk Galaxies
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrographs
• Two Red Clumps and the X-Shaped Milky Way Bulge
• Target Selection for the SDSS-IV APOGEE-2 Survey
• The Split Red Clump of the Galactic Bulge from OGLE-III
• Life in the fast lane: a direct view of the dynamics, formation, and evolution of the Milky Way's bar
• ARGOS IV: The Kinematics of the Milky Way Bulge
• The origin of the split red clump in the Galactic bulge of the Milky Way
• From the bulge to the outer disc: StarHorse stellar parameters, distances, and extinctions for stars in APOGEE DR16 and other spectroscopic surveys
• Separation of Stellar Populations by an Evolving Bar: Implications for the Bulge of the Milky Way
• Simultaneous calibration of spectro-photometric distances and the Gaia DR2 parallax zero-point offset with deep learning
• The APOGEE Data Release 16 Spectral Line List
• Detection of the old stellar component of the major Galactic bar
• Mapping the X-Shaped Milky Way Bulge
• The pattern speed of the Milky Way bar from transverse velocities
• K-Band Observations of Boxy Bulges. I. Morphology and Surface Brightness Profiles
• ARGOS II: The Galactic Bulge Survey
• A sharper view of Pal 5's tails: Discovery of stream perturbations with a novel non-parametric technique
• Bulges or Bars from Secular Evolution?
• Regular and Chaotic Dynamics of Triaxial Stellar Systems
• Tracing the long bar with red-clump giants
• Kinematics at the Edge of the Galactic Bulge: Evidence for Cylindrical Rotation
• Unifying boxy bulge and planar long bar in the Milky Way
• The Long Bar in the Milky Way. Corroboration of an old hypothesis
• The Milky Way bar and bulge revealed by APOGEE DR16 and Gaia EDR3
• Milky Way mass galaxies with X-shaped bulges are not rare in the local Universe
• The X-shaped Bulge of the Milky Way revealed by WISE
• Fluctuations in galactic bar parameters due to bar-spiral interaction
• The long Galactic bar as seen by UKIDSS Galactic Plane Survey
• The Orbital Evolution Induced by Baryonic Condensation in Triaxial Halos
• Tree-ring structure of Galactic bar resonance
• The Pristine Inner Galaxy Survey (PIGS) I: Tracing the kinematics of metal-poor stars in the Galactic bulge
• Effects of baryonic and dark matter substructure on the Pal 5 stream
• Chaotic Dispersal of Tidal Debris
• Revisiting the tension between fast bars and the $\Lambda$CDM paradigm
• The 4:1 Outer Lindblad Resonance of a long slow bar as a potential explanation for the Hercules stream
• The buildup of strongly barred galaxies in the TNG100 simulation
• A direct measurement of the distance to the Galactic center using the kinematics of bar stars
• Variations in the width, density, and direction of the Palomar 5 tidal tails
• Shepherding Tidal Debris with the Galactic Bar: The Ophiuchus Stream
• Trapped orbits and solar-neighbourhood kinematics
• A unified framework for the orbital structure of bars and triaxial ellipsoids
• External versus internal triggers of bar formation in cosmological zoom-in simulations
• A New Model for the Milky Way Bar
• Pattern Corotation Radii from Potential-Density Phase-Shifts for 153 OSUBGS Sample Galaxies
• The Bulge Radial Velocity Assay for RR Lyrae stars (BRAVA-RR) DR2: a Bimodal Bulge?
• Exploring the Sgr-Milky-Way-disc interaction using high resolution N-body simulations
• Spending too much time at the Galactic bar: chaotic fanning of the Ophiuchus stream
• Modeling the Milky Way as a Dry Galaxy
• The COMBS Survey -- II. Distinguishing the Metal-Poor Bulge from the Halo Interlopers
• Detection of the Milky Way spiral arms in dust from 3D mapping
• Dark Matter Trapping by Stellar Bars: The Shadow Bar
• Did Sgr cause the vertical waves in the solar neighbourhood?
• A Schwarzschild model of the Galactic bar with initial density from N-body simulations
• Applying Schwarzschild's orbit superposition method to barred or non-barred disc galaxies
• Using Torque to Understand Barred Galaxy Models
• The Milky Way Bulge: Observed properties and a comparison to external galaxies
• Using Commensurabilities and Orbit Structure to Understand Barred Galaxy Evolution
• Separatrix Divergence of Stellar Streams in Galactic Potentials
• The Coupling of Galactic Dark Matter Halos with Stellar Bars
• Orbital classification in an N-body bar
• Frequencies, chaos and resonances: a study of orbital parameters of nearby thick disc and halo stars
• A barred Milky Way surrogate from an N-body simulation

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• Timing the Milky Way bar formation and the accompanying radial migration episode
• Orbital support and evolution of flat profiles of bars (shoulders)
• Looking for a needle in a haystack: Measuring the length of a stellar bar
• Dynamical friction and feedback on galactic bars in the general fast-slow regime
• Precise Measurements of the LMC Bar's Geometry With Gaia DR3 and a Novel Solution to Crowding Induced Incompleteness in Star Counting
• The Pristine survey: XXV. The very metal-poor Galaxy: Chemodynamics through the follow-up of the Pristine-Gaia synthetic catalogue
• Exploring the impact of a rapidly decelerating bar on transforming bulge orbits into disc-like orbits
• Revealing Gas Inflows towards the Galactic Central Molecular Zone
• Accelerated phase-mixing in the stellar halo due to a rotating bar
• Bar-spiral interaction produces radial migration and star formation bursts
• Response of the LMC's Bar to a Recent SMC Collision and Implications for the SMC's Dark Matter Profile
• On the chaos induced by the Galactic bar on the orbits of nearby halo stars
• Probing the origins. I. Generalised Additive Model inference of birth radii for Milky Way stars in the solar vicinity
• Turbulent Pressure Heats Gas and Suppresses Star Formation in Galactic Bar Molecular Clouds
• Gas Transfer Between the Inner 3-kpc Disk and the Galactic Central Molecular Zone
• Disentanglement of the chemodynamical assembly: mapping the Milky Way disks
• Stirring Things Up: Bar-induced substructures in the stellar halo of a cosmological Milky Way analogue
• Quadrupole signature as a kinematic diagnostic to constrain bar properties : implications for the Milky Way
• Mapping the Milky Way with Gaia Bp/Rp spectra-IV: the broken and asymmetric density profile of the stellar disk traced by a large sample of red clumps
• Bar Properties and Star-by-Star Bar Membership via Action Conservation