The oblateness of the Milky Way dark matter halo from the stellar streams of NGC 3201, M68, and Palomar 5

Abstract

We explore constraints on the Milky Way dark matter halo oblateness using three stellar streams from globular clusters NGC 3201, M68, and Palomar 5. Previous constraints on the gravitational potential from dynamical equilibrium of stellar populations and distant Milky Way satellites are included. We model the dark halo as axisymmetric with axis ratio $q_{\rho }^{\mathrm{h}}$ and four additional free parameters of a two power-law density profile. The halo axis ratio, while barely constrained by the NGC 3201 stream alone, is required to be close to spherical by the streams of Palomar 5 ($q_{\rho }^{\mathrm{h}}=1.01\pm 0.09$) and M68 ($q_{\rho }^{\mathrm{h}}=1.14_{-0.14}^{+0.21}$), the latter allowing a more prolate shape. The three streams together are well fitted with a halo axis ratio $q_{\rho }^{\mathrm{h}}=1.06\pm 0.06$ and core radius $\sim$ 20 kpc. Our estimate of the halo shape agrees with previous studies using other observational data and is in tension with cosmological simulations predicting that most spiral galaxies have oblate dark matter halos with the short axis perpendicular to the disc. We discuss why the impact of the Magellanic Clouds tide is too small to change our conclusion on the halo axis ratio. We note that dynamical equilibrium of a spherical halo in the oblate disk potential implies an anisotropic dark matter velocity dispersion, larger along the vertical direction than the horizontal ones, which should relate to the assembly history of the Milky Way.

arXiv comment27 pages, 11 figures

References in corpus (123)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Gaia Data Release 2. Summary of the contents and survey properties
• The Structure of Cold Dark Matter Halos
• The Gaia mission
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Local Kinematics and the Local Standard of Rest
• The Galaxy in Context: Structural, Kinematic and Integrated Properties
• The Milky Way Tomography with SDSS: I. Stellar Number Density Distribution
• The mass distribution and gravitational potential of the Milky Way
• A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty
• The Connection between Galaxies and their Dark Matter Halos
• The Proper Motion of Sgr A*: II. The Mass of Sgr A*
• Mass models of the Milky Way
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• AGAMA: Action-based galaxy modelling architecture
• The Sagittarius Dwarf Galaxy: a Model for Evolution in a Triaxial Milky Way Halo
• Detection of massive tidal tails around the globular cluster Pal 5 with SDSS commissioning data
• A direct dynamical measurement of the Milky Way's disk surface density profile, disk scale length, and dark matter profile at 4 kpc < R < 9 kpc
• Great Circle tidal streams: evidence for a nearly spherical massive dark halo around the Milky Way
• Mean proper motions, space orbits and velocity dispersion profiles of Galactic globular clusters derived from Gaia DR2 data
• Constraining the Milky Way potential with a 6-D phase-space map of the GD-1 stellar stream
• The Circular Velocity Curve of the Milky Way from $5$ to $25$ kpc
• Accurate distances to Galactic globular clusters through a combination of Gaia EDR3, HST and literature data
• The Structure of the Milky Way's Bar Outside the Bulge
• The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream
• The Milky Way total mass profile as inferred from Gaia DR2
• The distribution of dark matter in galaxies
• Tango for three: Sagittarius, LMC, and the Milky Way
• Proper motions and dynamics of the Milky Way globular cluster system from Gaia DR2
• Stellar Streams Discovered in the Dark Energy Survey
• Spiral arms, bar shape and bulge microlensing in the Milky Way
• The local surface density of disc matter mapped by Hipparcos
• The Origin of the Bifurcation in the Sagittarius Stream
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: III. Constraints on the Flattening of the Galactic Halo
• Velocity trends in the debris of Sagittarius and the shape of the dark-matter halo of the Galaxy
• Precession of the Sagittarius stream
• Mass and shape of the Milky Way's dark matter halo with globular clusters from Gaia and Hubble
• The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution
• Globular Cluster Streams as Galactic High-Precision Scales - The Poster Child Palomar 5
• Ghostly Tributaries to the Milky Way: Charting the Halo's Stellar Streams with the Gaia DR2 catalogue
• Kinematics of the stellar halo and the mass distribution of the Milky Way using BHB stars
• The Orbital Histories of Magellanic Satellites Using Gaia DR2 Proper Motions
• Made-to-Measure models of the Galactic Box/Peanut bulge: stellar and total mass in the bulge region
• The shape of the inner Milky Way halo from observations of the Pal 5 and GD-1 stellar streams
• The Discovery of Tidal Tails Around NGC 5466
• Internal Alignment of the Halos of Disk Galaxies in Cosmological Hydrodynamic Simulations
• The Streams of the Gaping Abyss: A population of entangled stellar streams surrounding the Inner Galaxy
• More on the structure of tidal tails
• The mass of the Milky Way from satellite dynamics
• Detection of a 45 Degree Tidal Stream Associated with the Globular Cluster NGC 5466
• The Gravitational Potential Near the Sun From SEGUE K-dwarf Kinematics
• Evidence for a Triaxial Milky Way Dark Matter Halo from the Sagittarius Stellar Tidal Stream
• Rotation curve of the Milky Way from Classical Cepheids
• The impact of baryons on the spins and shapes of dark matter haloes
• The alignment and shape of dark matter, stellar, and hot gas distributions in the EAGLE and cosmo-OWLS simulations
• The mass of our Milky Way
• On the structure of tidal tails
• Constraining the Milky Way Halo Potential with the GD-1 stellar stream
• A comprehensive catalog of dark matter halo models for SPARC galaxies
• Measuring the Mass of the Large Magellanic Cloud with Stellar Streams Observed by $S^5$
• Milky Way Kinematics: Measurements at the Subcentral Point of the Fourth Quadrant
• Shape of Dark Matter Haloes in the Illustris Simulation: Effects of Baryons
• Dynamical modeling of tidal streams
• Limit on the LMC mass from a census of its satellites
• Generation of mock tidal streams
• Stream-orbit misalignment I: The dangers of orbit-fitting
• Weighing the local dark matter with RAVE red clump stars
• Stellar Streams and Clouds in the Galactic Halo
• The Gravitational Force Field of the Galaxy Measured From the Kinematics of RR Lyrae in Gaia
• The mechanics of tidal streams
• Halo globular clusters observed with AAOmega: dark matter content, metallicity and tidal heating
• galstreams: A Library of Milky Way Stellar Stream Footprints and Tracks
• The Pal 5 Star Stream Gaps
• Milky Way Mass and Potential Recovery Using Tidal Streams in a Realistic Halo
• Stellar Streams as Probes of Dark Halo Mass and Morphology: A Bayesian Reconstruction
• Dipping Our Toes in the Water: First Models of GD-1 as a Stream
• The power spectrum of the Milky Way: Velocity fluctuations in the Galactic disk
• Tidal Stream Morphology as an Indicator of Dark Matter Halo Geometry: the Case of Palomar 5
• NIHAO project II: Halo shape, phase-space density and velocity distribution of dark matter in galaxy formation simulations
• The global mass functions of 35 Galactic globular clusters: I. Observational data and correlations with cluster parameters
• What's Up in the Milky Way? The Orientation of the Disc Relative to the Triaxial Halo
• Feeling the pull, a study of natural Galactic accelerometers. I: photometry of the delicate stellar stream of the Palomar 5 globular cluster
• The Sagittarius Stream and Halo Triaxiality
• Evolution of Galaxy Shapes from Prolate to Oblate through Compaction Events
• Variations in the width, density, and direction of the Palomar 5 tidal tails
• Towards a fully consistent Milky Way disc model: Part 1 The local model based on kinematic and photometric data
• Alignments between galaxies, satellite systems and haloes
• Molecular Gas, Kinematics, and OB Star Formation in the Spiral Arms of the Southern Milky Way
• Inferring the gravitational potential of the Milky Way with a few precisely measured stars
• Butterfly in a Cocoon, Understanding the origin and morphology of Globular Cluster Streams: The case of GD-1
• Palomar 5 and its Tidal Tails: A Search for New Members in the Tidal Stream
• Dark matter halo shapes in the Auriga simulations
• Overview and stellar statistics of the expected Gaia Catalogue using the Gaia Object Generator
• Does the Sagittarius Stream constrain the Milky Way halo to be triaxial?
• A closer look at the spur, blob, wiggle, and gaps in GD-1
• The Milky Way Tomography with SDSS. V. Mapping the Dark Matter Halo
• Phlegethon, a nearby $75°$-long retrograde stellar stream
• First Gaia dynamical model of the Milky Way disc with six phase space coordinates: a test for galaxy dynamics
• Dynamical Evidence of a Solitonic Core of $10^9{M}_{\odot }$ in the Milky Way
• On the tidal tails of Milky Way globular clusters
• Detection of a 50 degree-long Trailing Tidal Tail for the Globular Cluster M5
• Kinematics of the Palomar 5 stellar stream from RR Lyrae stars
• Connecting the Milky Way potential profile to the orbital timescales and spatial structure of the Sagittarius Stream
• Feeling the pull, a study of natural Galactic accelerometers. II: kinematics and mass of the delicate stellar stream of the Palomar 5 globular cluster
• Is the Dark Halo of the Milky Way Prolate?
• Action-based distribution function modelling for constraining the shape of the Galactic dark matter halo
• An extended Pal 5 stream in Gaia DR2
• Stellar Disks in Aquarius Dark Matter Haloes
• Statistical detection of a tidal stream associated with the globular cluster M68 using Gaia data
• Milky Way rotation curve from proper motions of red clump giants
• Constraints on the Shape of the Milky Way Dark Matter Halo from Jeans Equations Applied to SDSS Data
• Discovery of Extended Tidal Tails around the Globular Cluster Palomar 13
• The tidal stream generated by the globular cluster NGC 3201
• Around The Way: Testing $\Lambda$CDM with Milky Way Stellar Stream Constraints
• Milky Way Kinematics. II. A uniform inner Galaxy HI terminal velocity curve
• Uncovering fossils of the distant Milky Way with UNIONS: NGC 5466 and its stellar stream
• Dark matter local density determination based on recent observations
• Applying Noether's theorem to matter in the Milky Way: evidence for external perturbations and non-steady-state effects from Gaia Data Release 2
• On the Hunt for the Origins of the Orphan--Chenab Stream: Detailed Element Abundances with APOGEE and Gaia
• Characterization and dynamics of the peculiar stream Jhelum, A tentative role for the Sagittarius dwarf galaxy
• Revisit NGC 5466 Tidal Stream with $Gaia$, SDSS/SEGUE and LAMOST
• The shape of the dark matter halo revealed from a hypervelocity star

Cited by in corpus (9)

• Modelling the Track of the GD-1 Stellar Stream Inside a Host with a Fermionic Dark Matter Core-Halo Distribution
• Cosmological Simulations of Stellar Halos with Gaia Sausage-Enceladus Analogues: Two Sausages, One Bun?
• First measurement of the triaxiality of the inner dark matter halo of the Milky Way
• A Vertically Orientated Dark Matter Halo Marks a Flip of the Galactic Disk
• Uncover 3D Dark Matter Distribution of the Milky Way by an Empirical Triaxial Orbit-Superposition Model: Method Validation
• Using two point correlation functions to understand the assembly histories of Milky Way-like galaxies
• A Cartesian catalog of 30 million Gaia sources based on second-order and Monte Carlo error propagation
• The mass and redshift dependence of halo star clustering
• Constraining the population of dark matter halo shapes using hierarchical inference with extragalactic stellar streams