CONSTRAINING THE MILKY WAY POTENTIAL WITH A SIX-DIMENSIONAL PHASE-SPACE MAP OF THE GD-1 STELLAR STREAM

By Sergey E. Koposov, Hans-Walter Rix, D. O. Astronomy, Heidelberg, Heidelberg · Germany, I. O. Astronomy, Cambridge, UK., Sternberg Astronomical Institute, Moscow and 4 more. 2009

268 citations recorded by the source corpus.

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 Vc = 224 ± 13 km s−1 and total potential flattening qΦ = 0.87+0.07−0.04. When we drop any informative priors on Vc, the GD-1 constraint becomes Vc = 221 ± 18 km s−1. Our 6D map of GD-1, therefore, yields the best current constraint on Vc and the only strong constraint on qΦ 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: qΦ,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.

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

`Skinny Milky Way please', says Sagittarius (2014, methodology): “This has been done most memorably by Koposov et al. (2010) in their modelling of the c© 2014 RAS GD-1 stellar stream.”
The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream (2018, background): “For example, both the GD-1 (Grillmair & Dionatos 2006) and the Palomar 5 streams (Odenkirchen et al. 2001) have proper motions closely aligned with their stream tracks (Koposov et al. 2010; Fritz & Kallivayalil 2015, respectively).”
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 (2013, background): “For example, Koposov et al. (2010) measured the total potential flattening at ≈ 8 kpc from the plane from fitting an orbit to the cold GD-1 stream, but found that the uncertainty in the mass of the disk did not allow for this to be turned into an interesting constraint on the halo’s flattening.”
FORMING REALISTIC LATE-TYPE SPIRALS IN A ΛCDM UNIVERSE: THE ERIS SIMULATION (2011, methodology): “…the errors with the values of Vc, = 221 ± 18 km s−1, M<60 = 4.0 ± 0.7 × 1011 M , and Mvir = 1.0 +0.3 −0.2 × 1012 M derived recently for the Milky Way using the narrow GD-1 stream of stars (for Vc, , Koposov et al. 2010) and halo stars as kinematic tracers (for M<60 and Mvir, Xue et al. 2008).”
THE MILKY WAY'S CIRCULAR-VELOCITY CURVE BETWEEN 4 AND 14 kpc FROM APOGEE DATA (2012, methodology): “The determination of Vc = 221± 18 km s−1 of Koposov et al. (2010) from fitting an orbit to the cold GD-1 stellar stream at R ∼ 10 kpc is clearly consistent with our measurement, although note that they assumed the Vφ,⊙−Vc = 5.25 km s −1 value for the solar motion from Dehnen & Binney (1998).”
LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) — The survey's science plan (2012, methodology): “2009, Koposov et al. 2010, Newberg et al. 2010, Li et al. 2012) have relied on handfuls of SEGUE plates that intersect the structures.”
The Milky Way’s stellar disk (2013, methodology): “…orbits, by determining an overall mass model for the Galaxy and its halo and interpolating inferences to (R0, z = 0) (e.g., Xue et al. 2008; Koposov et al. 2010; McMillan 2011), or by mapping and modeling the stellar velocities across a sufficiently large portion of the Disk (Bovy et…”
The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, methodology): “Sources for data points are: maser proper motions (PMs) and radial velocities (RVs) associated with high-mass disk stars (Reid et al. 2014, blue), inner Galaxy terminal velocities and outer disk velocities collected by Sofue et al. [2009, black (5 kpc < R < R0) and gray (elsewhere)], PMs of disk red”
Target Selection for the SDSS-IV APOGEE-2 Survey (2017, background): “Four additional streams are targeted using a variety of data to identify likely members: Pal-5 (Odenkirchen et al. 2001, 2002, 2003, 2009; Carlberg et al. 2012), GD1 (Koposov et al. 2010), Orphan (Newberg et al. 2010; Sesar et al. 2013; Casey et al. 2013, 2014), and the Sgr tail (Bellazzini et al. 2”
Galaxy Masses: A Review (2013, methodology): “By contrast, Koposov et al. (2010) found Vc = 221± 18 km s−1 by fitting an orbit to the GD-1 stellar stream.”