`Skinny Milky Way please', says Sagittarius

By S. Gibbons, V. Belokurov, N. Evans II. 2014

193 citations recorded by the source corpus.

Motivated by recent observations of the Sagittarius stream, we devise a rapid algorithm to generate faithful representations of the centroids of stellar tidal streams formed in a disruption of a progenitor of an arbitrary mass in an arbitrary potential. Our method works by releasing swarms of test particles at the Lagrange points around the satellite and subsequently evolving them in a combined potential of the host and the progenitor. We stress that the action of the progenitor's gravity is crucial to making streams that look almost indistinguishable from the N-body realizations, as indeed ours do. The method is tested on mock stream data in three different Milky Way potentials with increasing complexity, and is shown to deliver unbiased inference on the Galactic mass distribution out to large radii. When applied to the observations of the Sagittarius stream, our model gives a natural explanation of the stream's apocentric distances and the differential orbital precession. We, therefore, provide a new independent measurement of the Galactic mass distribution beyond 50 kpc. The Sagittarius stream model favours a light Milky Way with the mass 4.1 +/- 0.4 x 10^11 M_sun at 100 kpc, which can be extrapolated to 5.6 +/- 1.2 x 10^11 M_sun at 200 kpc. Such a low mass for the Milky Way Galaxy is in good agreement with estimates from the kinematics of halo stars and from the satellite galaxies (once Leo I is removed from the sample). It entirely removes the "Too Big To Fail Problem".

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/84a0e2d316f6ee68d3986f812112847f67ba87cf

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Citations in the corpus

The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, background): “Modeling stellar positions and velocities along the orbit of the Sagittarius dwarf galaxy, or matching the apocenter radii of its trailing and leading arms, leads to a range of enclosed masses of M 100kpc = 0.4– 2 × 1011 M (Gibbons et al. 2014).”
The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream (2018, methodology): “Our analysis relies on the rapid and accurate model stream production implemented using the mLCS technique (Gibbons et al. 2014) and considers a wide range of Galactic DM halo configurations.”
Evidence for an Intermediate-mass Milky Way from Gaia DR2 Halo Globular Cluster Motions (2018, background): “It would be interesting to re-visit the work of Gibbons et al. (2014) in the light of this.”
The milky way total mass profile as inferred from Gaia DR2 (2019, background): “…stars (e,g, Smith et al. 2007; Piffl et al. 2014; Fragione & Loeb 2017; Rossi et al. 2017; Deason et al. 2019b), the orbits of tidal streams (e.g. Gibbons et al. 2014; Bowden et al. 2015), the luminosity function of the MW satellites (e.g. Busha et al. 2011; Cautun et al. 2014b) and the dynamics…”
Stellar Streams Discovered in the Dark Energy Survey (2018, methodology): “Milky Way Gravitational Potential Stellar streams can be used to constrain the Milky Way gravitational potential (e.g., Johnston et al. 2005; Koposov et al. 2010; Law & Majewski 2010; Gibbons et al. 2014; Bowden et al. 2015; Küpper et al. 2015b; Bovy et al. 2016).”
BEASTS OF THE SOUTHERN WILD: DISCOVERY OF NINE ULTRA FAINT SATELLITES IN THE VICINITY OF THE MAGELLANIC CLOUDS (2015, background): “If the LMC is on first infall and if the mass of the Milky Way is 1 × 1012M⊙ (e.g. Gibbons et al. 2014), then the orbital period is 9-12 Gyr.”