THE SPACE MOTION OF LEO I: THE MASS OF THE MILKY WAY'S DARK MATTER HALO

By M. Boylan-Kolchin, James S. Bullock, S. Sohn, G. Besla, R. P. van der Marel. 2012

163 citations recorded by the source corpus.

We combine our Hubble Space Telescope measurement of the proper motion of the Leo I dwarf spheroidal galaxy (presented in a companion paper) with the highest resolution numerical simulations of Galaxy-size dark matter halos in existence to constrain the mass of the Milky Way's dark matter halo (Mvir, MW). Despite Leo I's large Galactocentric space velocity (200 km s−1) and distance (261 kpc), we show that it is extremely unlikely to be unbound if Galactic satellites are associated with dark matter substructure, as 99.9% of subhalos in the simulations are bound to their host. The observed position and velocity of Leo I strongly disfavor a low-mass Milky Way: if we assume that Leo I is the least bound of the Milky Way's classical satellites, then we find that Mvir, MW > 1012 M☉ at 95% confidence for a variety of Bayesian priors on Mvir, MW. In lower mass halos, it is vanishingly rare to find subhalos at 261 kpc moving as fast as Leo I. Should an additional classical satellite be found to be less bound than Leo I, this lower limit on Mvir, MW would increase by 30%. Imposing a mass-weighted ΛCDM prior, we find a median Milky Way virial mass of Mvir, MW = 1.6 × 1012 M☉, with a 90% confidence interval of [1.0–2.4] × 1012 M☉. We also confirm a strong correlation between subhalo infall time and orbital energy in the simulations and show that proper motions can aid significantly in interpreting the infall times and orbital histories of satellites.

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/5e534643148332a4ade7dba89a4b01ff60ba4009

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Citations in the corpus

THIRD-EPOCH MAGELLANIC CLOUD PROPER MOTIONS. II. THE LARGE MAGELLANIC CLOUD ROTATION FIELD IN THREE DIMENSIONS (2013, background): “…studies have focused primarily on the satellites of the Milky Way (Kallivayalil et al. 2006a, hereafter K06; Kallivayalil, van der Marel & Alcock 2006b; Piatek & Prior 2008, and references therein; Pryor, Piatek & Olszewski 2010; Lépine et al. 2011; Sohn et al. 2013; Boylan-Kolchin et al. 2013).”
Gaia DR2 proper motions of dwarf galaxies within 420 kpc (2018, background): “Boylan-Kolchin et al. (2013) addressed this topic in detail for the case of Leo I.”
ELVIS: Exploring the Local Volume in Simulations (2013, background): “…millions (rounded to the nearest million) within the high-resolution radius Rres. h Number of subhaloes within Rres with Vmax > 8 km/s. i Taken from Boylan-Kolchin et al. (2013) with 90% c.l. quoted. j As enumerated in McConnachie (2012). k The LMC, from Olsen et al. (2011) l Combining results…”
Too big to fail in the Local Group (2014, background): “…mass must be below ∼7 × 1011 M to eliminate the massive failures (see also BoylanKolchin et al. 2012; Purcell & Zentner 2012; Wang et al. 2012), which is in conflict with large-scale dynamical mass estimates of the MW (van der Marel et al. 2012; Boylan-Kolchin et al. 2013, and references therein).”
Galactic Searches for Dark Matter (2012, background): “Most recent proper motions indicate that it may be bound to the Galaxy (Sohn et al., 2012; Boylan-Kolchin et al., 2012).”
Using the Milky Way satellites to study interactions between cold dark matter and radiation (2014, background): “…by calculations that attempt to reconstruct the MW mass distribution based on the measured kinematics of the observed satellites and stars (Xue et al. 2008; Boylan-Kolchin et al. 2013; Piffl et al. 2014), we consider DM haloes to be MW-like if their mass is in the range (0.8− 2.7)× 1012M .”
The APOSTLE project: Local Group kinematic mass constraints and simulation candidate selection (2015, background): “…of tracers such as satellite galaxies, halo stars, or tidal debris (see e.g. Battaglia et al. 2005; Sales et al. 2007; Smith et al. 2007; Xue et al. 2008; Watkins, Evans & An 2010; Deason et al. 2012; Boylan-Kolchin et al. 2013; Barber et al. 2014; Piffl et al. 2014, for some recent studies).”
CONSTRAINING THE MILKY WAY'S HOT GAS HALO WITH O vii AND O viii EMISSION LINES (2014, background): “Current estimates for the Milky Way’s virial mass have a range of 1.0 − 2.4 × 1012M⊙ (Boylan-Kolchin et al. 2013).”
ON THE SHOULDERS OF GIANTS: PROPERTIES OF THE STELLAR HALO AND THE MILKY WAY MASS DISTRIBUTION (2014, background): “…Tremaine 1990; Smith et al. 2007; Piffl et al. 2014), the orbital evolution ofthe satellite galaxies and globular clusters (Lin & Lynden-Bell 1982; Boylan-Kolchin et al. 2013), modeling the tidal streams (Law et al. 2005; Newberg et al. 2010; Sanders & Binney 2013b; Sanderson & Helmi 2013), the…”
The RAVE survey : the Galactic escape speed and the mass of the Milky Way (2013, methodology): “Another important constraint for the Galactic halo is the space motion of the satellite galaxy Leo I. Boylan-Kolchin et al. (2013) show that in the ΛCDM paradigm, it is extremely unlikely that a galaxy like the Milky Way has an unbound closeby satellite galaxy.”
Near-Field Cosmology with Extremely Metal-Poor Stars (2015, background): “Associated with the Galaxy’s luminous material is a massive halo of dark matter, extending to ∼300 kpc from the Galactic center, and having a mass in the range 1.0 – 2.4×1012 M⊙ (at the 90% confidence level) (Boylan-Kolchin et al. 2013, and references therein).”