Constraining the Milky Way Potential With a Six-dimensional Phase-space Map of the Gd-1 Stellar Stream
Year: 2010
Type: article
Abstract: The narrow GD-1 stream of stars, spanning 60° on the sky at a distance of ∼10 kpc from the Sun and ∼15 kpc from the Galactic center, is presumed to be debris from a tidally disrupted star cluster that traces out a test-particle orbit in the Milky Way halo. We combine Sloan Digital Sky Survey (SDSS) photometry, USNO-B astrometry, and SDSS and Calar Alto spectroscopy to construct a complete, empirical six-dimensional (6D) phase-space map of the stream. We find that an eccentric orbit in a flattened isothermal potential describes this phase-space map well. Even after marginalizing over the stream orbital parameters and the distance from the Sun to the Galactic center, the orbital fit to GD-1 places strong constraints on the circular velocity at the Sun's radius V c = 224 ± 13 km s −1 and total potential flattening q Φ = 0.87 +0.07 −0.04 . When we drop any informative priors on V c , the GD-1 constraint becomes V c = 221 ± 18 km s −1 . Our 6D map of GD-1, therefore, yields the best current constraint on V c and the only strong constraint on q Φ at Galactocentric radii near R ∼ 15 kpc. Much, if not all, of the total potential flattening may be attributed to the mass in the stellar disk, so the GD-1 constraints on the flattening of the halo itself are weak: q Φ,halo > 0.89 at 90% confidence. The greatest uncertainty in the 6D map and the orbital analysis stems from the photometric distances, which will be obviated by GAIA .
Source: The Astrophysical Journal
Authors: Sergey E. Koposov, Hans-Walter Rix, David W. Hogg
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: National Aeronautics and Space Administration, Alexander von Humboldt-Stiftung, Princeton University, Ohio State University, University of Washington, Johns Hopkins University, University of Pittsburgh, Case Western Reserve University, Drexel University, Universität Basel, University of Portsmouth, New Mexico State University, Deutsche Forschungsgemeinschaft, Russian Foundation for Basic Research, Chinese Academy of Sciences, Max-Planck-Institut für Astronomie, Science and Technology Facilities Council, Kavli Institute for Theoretical Physics, University of California, Santa Barbara, U.S. Naval Observatory, Fermilab, Los Alamos National Laboratory
OpenAlex ID: W2045976894