Milky Way Mass and Potential Recovery Using Tidal Streams in a Realistic Halo

Abstract

We present a new method for determining the Galactic gravitational potential based on forward modeling of tidal stellar streams. We use this method to test the performance of smooth and static analytic potentials in representing realistic dark matter halos, which have substructure and are continually evolving by accretion. Our FAST-FORWARD method uses a Markov Chain Monte Carlo algorithm to compare, in 6D phase space, an "observed" stream to models created in trial analytic potentials. We analyze a large sample of streams evolved in the Via Lactea II (VL2) simulation, which represents a realistic Galactic halo potential. The recovered potential parameters are in agreement with the best fit to the global, present-day VL2 potential. However, merely assuming an analytic potential limits the dark matter halo mass measurement to an accuracy of 5 to 20%, depending on the choice of analytic parametrization. Collectively, mass estimates using streams from our sample reach this fundamental limit, but individually they can be highly biased. Individual streams can both under- and overestimate the mass, and the bias is progressively worse for those with smaller perigalacticons, motivating the search for tidal streams at galactocentric distances larger than 70 kpc. We estimate that the assumption of a static and smooth dark matter potential in modeling of the GD-1 and Pal5-like streams introduces an error of up to 50% in the Milky Way mass estimates.

12 pages, 6 figures, submitted to ApJ; more information on our stream sample and a movie of the potential recovery method used can be found at http://www.astro.yale.edu/abonaca/research/potential_recovery.html

References in corpus (11)

• Detection of a 63 Degree Cold Stellar Stream in the Sloan Digital Sky Survey
• On the structure of tidal tails
• The mechanics of tidal streams
• The PAndAS Field of Streams: stellar structures in the Milky Way halo toward Andromeda and Triangulum
• Discovery of a cold stellar stream in the ATLAS DR1 data
• The Graininess of Dark Matter Haloes
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• The Tidal Tails of 47 Tucanae
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Cited by in corpus (17)

• Globular Cluster Streams as Galactic High-Precision Scales - The Poster Child Palomar 5
• Generation of mock tidal streams
• Dipping Our Toes in the Water: First Models of GD-1 as a Stream
• On feathers, bifurcations and shells: the dynamics of tidal streams across the mass scale
• Variations in the width, density, and direction of the Palomar 5 tidal tails
• Modeling the gravitational potential of a cosmological dark matter halo with stellar streams
• Simulating tidal streams in a high resolution dark matter halo
• On the stability of tidal streams in action space
• Exploding Satellites -- The Tidal Debris of the Ultra-Faint Dwarf Galaxy Hercules
• Quantifying tidal stream disruption in a simulated Milky Way
• The Milky Way, Coming into Focus: Precision Astrometry Probes its Evolution, and its Dark Matter
• The effect of secular galactic growth on the evolution of star clusters
• Forward and Back: Kinematics of the Palomar 5 Tidal Tails
• A Ghost in Boötes: The Least Luminous Disrupted Dwarf Galaxy
• Dynamical Properties of Collisionless Star Streams
• An Orbit Fit to Likely Hermus Stream Stars
• Multi-wavelength observations of the Galactic X-ray binaries IGR J20155+3827 and Swift J1713.4-4219