The RAVE Survey: Constraining the Local Galactic Escape Speed

By M. Smith, G. Ruchti, A. Helmi, R. Wyse, Jon P. Fulbright, Kenneth C. Freeman, J. Navarro, G. Seabroke, Matthias Steinmetz, M. Williams and 13 more. Proceedings of the International Astronomical Union, 2006

524 citations recorded by the source corpus.

Abstract We report new constraints on the local escape speed of our Galaxy. Our analysis is based on a sample of high velocity stars from the RAVE survey and two previously published datasets (the Geneva-Copenhagen survey and the Beers et al. catalogue of metal-poor stars). We use cosmological simulations of disk galaxy formation to motivate our assumptions on the shape of the velocity distribution, allowing for a significantly more precise measurement of the escape velocity compared to previous studies. We find that the escape velocity lies within the range 492 km s−1 < vesc <594 kms (90% confidence), with a median likelihood of 536 kms. The fact that v2esc is significantly greater than 2v2circ implies that there must be a significant amount of mass exterior to the Solar circle, i.e. this convincingly demonstrates the presence of a dark halo in the Galaxy. For a simple isothermal halo, one can calculate that the minimum radial extent is ~54 kpc. We use our constraints on vesc to determine the mass of the Milky Way halo for three halo profiles. For example, an adiabatically contracted NFW halo model results in a virial mass of 1.31+0.97−0.49 × 1012M⊙ and virial radius of 297+60−44 kpc (90% confidence). For this model the circular velocity at the virial radius is 141+27−19kms. Although our halo masses are model dependent, we find that they are in good agreement with each other.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

Lectures on Dark Matter Physics (2016, background): “Measurements of the fastest stars in the Galaxy bound the escape velocity to be within 498–608 km/s, to 90% confidence [67].”
KINEMATICS OF THE STELLAR HALO AND THE MASS DISTRIBUTION OF THE MILKY WAY USING BLUE HORIZONTAL BRANCH STARS (2012, background): “The orbital evolution of the Magellanic clouds (Lin & Lynden-Bell 1982; Besla et al. 2007), the local escape speed (Smith et al. 2007), the timing argument (Li & White 2008) and the study of the kinematic of the tracers population (Kochanek 1996; Xue et al. 2008; Gnedin et al. 2010; Watkins et al.…”
ON THE SHOULDERS OF GIANTS: PROPERTIES OF THE STELLAR HALO AND THE MILKY WAY MASS DISTRIBUTION (2014, background): “…mass distribution of the Galaxy, e.g., the timing argument (Kahn & Woltjer 1959; Li & White 2008), the local escape speed (Leonard & 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…”
Formation of Double Neutron Star Systems (2017, background): “The possibility that a fair fraction of bound DNS systems leave our Galaxy as a result of very large kicks also seems unlikely given that the local escape velocity in the Galactic rest frame is quite large, about 550 km s−1 (Smith et al. 2007).”
Galactic accretion and the outer structure of galaxies in the CDM model (2013, background): “13 by M31 (black point; Watkins et al. 2010; Courteau et al. 2011) and the Milky Way (grey box; Smith et al. 2007; Bell et al. 2008; Li & White 2008).”
FORMING REALISTIC LATE-TYPE SPIRALS IN A ΛCDM UNIVERSE: THE ERIS SIMULATION (2011, methodology): “2/V200 ratios from Smith et al. (2007) and Xue et al. (2008), were computed by Dutton et al. (2010) from these data sets after converting different virial mass definitions and for an assumed Milky Way’s V2.”
The Galaxy and its stellar halo: insights on their formation from a hybrid cosmological approach (2008, unknown): “1 Latest observational results give Vmax ∼ 180 − 220 kms−1 and a mass MMW ∼ 1 × 1012 M⊙ (Battaglia et al. 2005; Smith et al. 2007).”
Mass and shape of the Milky Way’s dark matter halo with globular clusters from Gaia and Hubble (2018, background): “…the outermost isolated ones are excluded, e.g. Gonzalez et al. 2013; Eadie & Harris 2016; Sohn et al. 2018), estimates of the escape velocity (e.g. Smith et al. 2007; Piffl et al. 2014a), the velocity distribution of either fast moving stars (e.g. Gnedin et al. 2010) or the dynamics of nearby…”
Galaxies–intergalactic medium interaction calculation – I. Galaxy formation as a function of large-scale environment (2009, background): “…than vc and therefore comparable to vw, particularly in cases where the potential of the halo is steepened by the stellar mass at the centre (e.g. Smith et al. 2007), Dalla Vecchia & Schaye (2008) demonstrated that the efficacy of winds is determined by the ISM pressure: winds become ineffective…”
Galaxy-induced transformation of dark matter haloes (2009, background): “The possibility that the virial velocity of the Milky Way is significantly lower than 220 km/s has indeed been advocated by a number of recent observational studies (Smith et al., 2007; Sales et al., 2007; Xue et al., 2008).”
Colloquium: Annual modulation of dark matter (2013, background): “The Radial Velocity Experiment (RAVE) survey finds that the 90% confidence range is 498–608 km=s (Smith et al., 2007).”
ON THE LACK OF EVOLUTION IN GALAXY STAR FORMATION EFFICIENCY (2012, background): “This same narrow range of halo and stellar masses (which includes the stellar and halo mass of the Milky Way; Klypin et al. 2002; Flynn et al. 2006; Smith et al. 2007; Busha et al. 2011) is responsible for most star formation since at least z = 4, due to the constancy of the star formation…”
Dark matter direct-detection experiments (2015, methodology): “The commonly used value of 544 km/s is the likelihood median calculated using data from the RAVE survey [146].”
The missing massive satellites of the Milky Way (2012, unknown): “…reported by estimates based on (i) the radial velocity dispersion of Milky Way satellites and halo stars (Battaglia et al. 2005; Sales et al. 2007); (ii) the escape speed in the solar neighbourhood (Smith et al. 2007); or (iii) the kinematics of halo blue horizontal branch stars (Xue et al. 2008).”
Directional detection of dark matter with two-dimensional targets (2016, methodology): “We assume the Standard Halo Model (SHM) [38] for g(v), with v0 220 km/s [39] and vesc 550 km/s [40]”
Milky Way mass models for orbit calculations (2012, background): “The escape velocity at the Sun’s position is about 616 km s−1, thereby lying very close to the 90%-confidence limit 498 km s−1 < vesc, < 608 km s−1 of A137, page 6 of 13 Smith et al. (2007).”
Detecting superlight dark matter with Fermi-degenerate materials (2015, methodology): “Here fMB is the velocity distribution of DM, which we take to be a modified MaxwellBoltzmann distribution [58],”