Predicted Trends in Milky Way Bulge Proper Motion Rotation Curves: future Prospects for HST and LSST

Abstract

We use an $N$-body+smoothed particle hydrodynamics simulation of an isolated barred galaxy to study the age dependence of bulge longitudinal proper motion (${\mu }_l$) rotation curves. We show that close to the minor axis ($|l|\sim 0^{\circ }$) the relatively young stars rotate more rapidly than the old stars, as found by Hubble Space Telescope in the Milky Way's (MW's) bulge. This behaviour would be expected also if the MW were unbarred. At larger $|l|$ a different behaviour emerges. Because younger stars trace a strong bar, their galactocentric radial motions dominate their ${\mu }_l$ at $|l|\sim 6^{\circ }$, leading to a reversal in the sign of $⟨{\mu }_l⟩$. This results in a rotation curve with forbidden velocities (negative $⟨{\mu }_l⟩$ at positive longitudes, and positive $⟨{\mu }_l⟩$ at negative longitudes). The old stars, instead, trace a much weaker bar and thus their kinematics are more axisymmetric, resulting in no forbidden velocities. We develop metrics of the difference in the $⟨{\mu }_l⟩$ rotation curves of young and old stars, and forbidden velocities. We use these to predict the locations where rotation curve reversals can be observed by HST and the Vera Rubin Telescope. Such measurements would represent support for the amplitude of the bar being a continuous function of age, as predicted by kinematic fractionation, in which the bar strength variations are produced purely by differences in the random motions of stellar populations at bar formation.

arXiv comment20 pages, 18 figures, 2 tables, published in MNRAS

References in corpus (92)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• The NumPy array: a structure for efficient numerical computation
• galpy: A Python Library for Galactic Dynamics
• A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty
• Star Formation and Feedback in Smoothed Particle Hydrodynamic Simulations--I. Isolated Galaxies
• Gasoline: An adaptable implementation of TreeSPH
• Constraints from Dynamical Friction on the Dark Matter Content of Barred Galaxies
• Structural Properties of Pseudo-Bulges, Classical Bulges and Elliptical Galaxies: an SDSS Perspective
• The Frequency of Barred Spiral Galaxies in the Near-IR
• Morphology, photometry and kinematics of N-body bars. I Three models with different halo central concentrations
• The Secular Evolution of Disk Structural Parameters
• Age and Metallicity Distribution of the Galactic Bulge from Extensive Optical and Near-IR Stellar Photometry
• 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 Near-Infrared Study of 2MASS Bars in Local Galaxies: An Anchor for High Redshift Studies
• Secular Evolution in Disk Galaxies
• The Structure of the Milky Way's Bar Outside the Bulge
• Our Milky Way as a Pure-Disk Galaxy -- A Challenge for Galaxy Formation
• The population of barred galaxies in the local universe I. Detection and characterisation of bars
• ARGOS III: Stellar Populations in the Galactic Bulge of the Milky Way
• Two Red Clumps and the X-Shaped Milky Way Bulge
• Target Selection for the SDSS-IV APOGEE-2 Survey
• The Genesis of the Milky Way's Thick Disk via Stellar Migration
• The Bulge Radial Velocity Assay (BRAVA): II. Complete Sample and Data Release
• The metallicity distribution of bulge clump giants in Baade's Window
• Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy
• Bars in Disk-Dominated and Bulge-Dominated Galaxies at z~0: New Insights from ~3600 SDSS Galaxies
• Life in the fast lane: a direct view of the dynamics, formation, and evolution of the Milky Way's bar
• Chemodynamical history of the Galactic Bulge
• ARGOS IV: The Kinematics of the Milky Way Bulge
• Improved GRAVITY astrometric accuracy from modeling of optical aberrations
• The origin of the split red clump in the Galactic bulge of the Milky Way
• Orbital dynamics of three-dimensional bars: I. The backbone of 3D bars. A fiducial case
• Separation of Stellar Populations by an Evolving Bar: Implications for the Bulge of the Milky Way
• Stellar Proper Motions in the Galactic Bulge from deep HST ACS/WFC Photometry
• Insights on the Milky Way bulge formation from the correlations between kinematics and metallicity
• The GIRAFFE Inner Bulge Survey (GIBS) III. Metallicity distributions and kinematics of 26 Galactic bulge fields
• Chemodynamics of barred galaxies in cosmological simulations: On the Milky Way's quiescent merger history and in-situ bulge
• Mapping the X-Shaped Milky Way Bulge
• Transiting extrasolar planetary candidates in the Galactic bulge
• The Gaia-ESO Survey: metallicity and kinematic trends in the Milky Way bulge
• HST/WFPC2 proper motions in two bulge fields: kinematics and stellar population of the Galactic bulge
• The First Detection of Blue Straggler Stars in the Milky Way Bulge
• The properties of the Galactic bar implied by gas kinematics in the inner Milky Way
• Stellar density profile and mass of the Milky Way Bulge from VVV data
• The X-shaped Bulge of the Milky Way revealed by WISE
• The formation of stellar nuclear discs in bar-induced gas inflows
• The Frequency and Stellar-Mass Dependence of Boxy/Peanut-Shaped Bulges in Barred Galaxies
• The disc origin of the Milky Way bulge: Dissecting the chemo-morphological relations using N-body simulations and APOGEE
• The Age and Structure of the Galactic Bulge from Mira Variables
• A Vertical Resonance Heating Model for X- or Peanut-Shaped Galactic Bulges
• Star formation history of the Galactic bulge from deep HST imaging of low reddening windows
• APOGEE Kinematics I: Overview of the Kinematics of the Galactic Bulge as Mapped by APOGEE
• Three Mechanisms for Bar Thickening
• Field Stars and Clusters of the Galactic Bulge: Implications for Galaxy Formation
• The inner Galactic bulge: evidence for a nuclear bar?
• Chemodynamical Modelling of the Galactic Bulge and Bar
• Stellar Ages through the Corners of the Boxy Bulge
• Young stars in an old bulge: a natural outcome of internal evolution in the Milky Way
• The disc origin of the Milky Way bulge
• The WFC3 Galactic Bulge Treasury Program: Relative Ages of Bulge Stars of High and Low Metallicity
• Growth of a peanut shaped bulge via resonant trapping of stellar orbits in the vertical Inner Lindblad Resonances
• Evidence of a Metal Rich Galactic Bar from the Vertex Deviation of the Velocity Ellipsoid
• The WFC3 Galactic Bulge Treasury Program: Metallicity Estimates for the Stellar Population and Exoplanet Hosts
• The Bulge Radial Velocity Assay for RR Lyrae stars (BRAVA-RR) DR2: a Bimodal Bulge?
• Stochasticity in N-body Simulations of Disc Galaxies
• 3D kinematics through the X-shaped Milky Way bulge
• Age Demographics of the Milky Way Disk and Bulge
• Formation, vertex deviation and age of the Milky Way's bulge: input from a cosmological simulation with a late-forming bar
• N-body simulation insights into the X-shaped bulge of the Milky Way: Kinematics and distance to the Galactic Centre
• Metallicity and kinematics of the bar in-situ
• Transverse kinematics of the Galactic bar-bulge from VVV and Gaia
• The Metallicity Distribution of the Milky Way Bulge
• Revealing the cosmic evolution of boxy/peanut-shaped bulges from HST COSMOS and SDSS
• Formation of the Galactic bulge from a two-component stellar disk: Explaining cylindrical rotation and vertical metallicity gradient
• Box/peanut-shaped bulges in action space
• First Detection of the White-Dwarf Cooling Sequence of the Galactic Bulge
• A Kiloparsec-Scale Nuclear Stellar Disk in the Milky Way as a Possible Explanation of the High Velocity Peaks in the Galactic Bulge
• Stars behind bars II: A cosmological formation scenario for the Milky Way's central stellar structure
• Reinforcing the link between the double red clump and the X-shaped bulge of the Milky Way
• The disc origin of the Milky Way bulge: On the necessity of the thick disc
• Kinematics of RR Lyrae stars in the Galactic bulge with OGLE-IV and Gaia DR2
• Violent Buckling Benefits Galactic Bars
• The effect of warm gas on the buckling instability in galactic bars
• Chemically-dissected rotation curves of the Galactic Bulge from Main Sequence proper motions
• The chemistry of stars in the bar of the Milky Way
• Comparing the properties of the X-shaped bulges of NGC 4710 and the Milky Way with MUSE
• The Mira-based distance to the Galactic centre
• 4MOST Consortium Survey 4: Milky Way Disc and Bulge High-Resolution Survey (4MIDABLE-HR)
• Blanco DECam Bulge Survey (BDBS) III: A new view of the double red clump in the Milky Way bulge through luminosity and color distribution
• Peanut-shaped metallicity distributions in bulges of edge-on galaxies: the case of NGC 4710
• Predicted Stellar Kinematics of a Kiloparsec-Scale Nuclear Disc (or Ring) in the Milky Way

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• The imprint of clump formation at high redshift. II. The chemistry of the bulge
• Blanco DECam Bulge Survey (BDBS) V. Cleaning the foreground populations from Galactic bulge colour-magnitude diagrams using Gaia EDR3
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• The chemical and spatial variations of the bulge's velocity ellipsoids