THE MILKY WAY'S CIRCULAR-VELOCITY CURVE BETWEEN 4 AND 14 kpc FROM APOGEE DATA

By Jo Bovy, C. Allende Prieto, Timothy C. Beers, D. Bizyaev, L. D. da Costa, K. Cunha, G. Ebelke, Daniel J. Eisenstein, P. Frinchaboy, A. G. García Pérez and 23 more. 2012

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We measure the Milky Way's rotation curve over the Galactocentric range 4 kpc ≲ R ≲ 14 kpc from the first year of data from the Apache Point Observatory Galactic Evolution Experiment. We model the line-of-sight velocities of 3365 stars in 14 fields with b = 0° between 30° ⩽ l ⩽ 210° out to distances of 10 kpc using an axisymmetric kinematical model that includes a correction for the asymmetric drift of the warm tracer population (σR ≈ 35 km s−1). We determine the local value of the circular velocity to be Vc(R0) = 218 ± 6 km s−1 and find that the rotation curve is approximately flat with a local derivative between −3.0 km s−1 kpc−1 and 0.4 km s−1 kpc−1. We also measure the Sun's position and velocity in the Galactocentric rest frame, finding the distance to the Galactic center to be 8 kpc < R0 < 9 kpc, radial velocity VR, ☉ = −10 ± 1 km s−1, and rotational velocity Vϕ, ☉ = 242+10− 3 km s−1, in good agreement with local measurements of the Sun's radial velocity and with the observed proper motion of Sgr A*. We investigate various systematic uncertainties and find that these are limited to offsets at the percent level, ∼2 km s−1 in Vc. Marginalizing over all the systematics that we consider, we find that Vc(R0) < 235 km s−1 at >99 % confidence. We find an offset between the Sun's rotational velocity and the local circular velocity of 26 ± 3 km s−1, which is larger than the locally measured solar motion of 12 km s−1. This larger offset reconciles our value for Vc with recent claims that Vc ≳ 240 km s−1. Combining our results with other data, we find that the Milky Way's dark-halo mass within the virial radius is ∼8 × 1011 M☉.

Subfields: Artificial Intelligence, Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/453efd9f13e70d8324ccff8e7e4d45aa9298072f

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Citations in the corpus

Timing analysis for 20 millisecond pulsars in the Parkes Pulsar Timing Array (2015, methodology): “Bovy et al. (2012) find that the uncertainty for the circular velocity of local sources is approximately 3 per cent by using data from the Apache Point Observatory Galactic Evolution Experiment.”
Theoretical Challenges in Galaxy Formation (2016, background): “Typically mass estimates are in the range of 1−2×1012M (Bland-Hawthorn & Gerhard 2016; Bovy et al. 2012; Li & White 2008; Watkins, Evans & An 2010; Xue et al. 2008).”
Chemodynamics of the Milky Way - I. The first year of APOGEE data (2013, methodology): “…al. 2013b), or – Due to yet another selection effect related to the inhomogeneous coverage of the Galactic disc(s) by finite-sightline observations (Bovy et al. 2012c), which is present in all the currently available large-scale Galactic survey data (APOGEE, 22 Rg ≈ Rmed is the orbital »guiding…”
The local dark matter density (2014, background): “But even accounting for this, the error bars appear to remain static with time or grow despite the arrival of data from SDSS.”
The Milky Way’s stellar disk (2013, methodology): “In particular for σz , which Bovy et al. (2012c) have investigated in detail, the degree of isothermally is remarkable (see Fig.”
emcee: The MCMC Hammer (2012, unknown): “…2013; Cieza et al. 2013; Akeret et al. 2012; Huppenkothen et al. 2012; Monnier et al. 2012; Morton 2012; Crossfield et al. 2012; Roškar et al. 2012; Bovy et al. 2012a, 2012b, 2012c; Brown et al. 2012; Brammer et al. 2012; Bussmann et al. 2012; Lang & Hogg 2012; Olofsson et al. 2012; Dorman et al.…”
The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, methodology): “The GCS survey covers the full sky but is confined to the Solar Neighborhood; the SEGUE, RAVE, and APOGEE surveys penetrate deeper into the Galaxy than earlier stellar surveys.”
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, methodology): “In a recent series of papers, we (Bovy et al. 2012c,d) demonstrated that these constitute structurally-simple disk populations.”
Made-to-measure models of the Galactic box/peanut bulge: stellar and total mass in the bulge region (2015, background): “This velocity scaling is first fixed to some reference value using the circular velocity at the radius of the Sun from Bovy et al. (2012) (218kms−1).”
STARS, GAS, AND DARK MATTER IN THE SOLAR NEIGHBORHOOD (2015, methodology): “This is marginally consistent with the result of Bovy et al. (2012b), who found M30 1 pc 2 - .”
The mass distribution and gravitational potential of the Milky Way (2016, background): “These arguments still hold, and suggest that both theSchönrich(2012) and Bovy et al.(2012b) results should be treated with some scepticism.”
Constraining the Galaxy's dark halo with RAVE stars (2014, background): “The low-latitude infrared survey APOGEE (Allende Prieto et al. 2008) should resolve this issue, but to date it has not yielded physically plausible results (Bovy et al. 2012b).”
Dynamical modelling of the galactic bulge and bar: the Milky Way's pattern speed, stellar and dark matter mass distribution (2016, result): “…tangential velocity of 250kms−1, in good agreement with several recent measurements of 248±6kms−1 (Schönrich 2012, from SEGUE data), 242+10−3 kms −1 (Bovy et al. 2012, from APOGEE data), 244± 5kms−1 (Sharma et al. 2014, from RAVE data) and 251± 5kms−1 (Reid et al. 2014, from maser velocities).”
`Skinny Milky Way please', says Sagittarius (2014, methodology): “Attempts to gauge the total mass of the Milky Way have been made using a variety of stellar kinematic tracer populations (see e.g. Smith et al. 2007; Xue et al. 2008; Bovy et al. 2012).”
galpy: A python LIBRARY FOR GALACTIC DYNAMICS (2014, methodology): “…density at the solar circle of Holmberg & Flynn (2000): ρ(R0, Z = 0) = 0.10 ± 0.01 M pc−3; 6. the constraint on the logarithmic slope of the rotation curve from Bovy et al. (2012), represented in the same way as in Equation (41) in Bovy & Rix (2013); 7. the measurement of the total mass…”
The number and size of subhalo-induced gaps in stellar streams (2016, methodology): “For Pal 5, we assume a circular velocity of 220 km/s at a radius of 13 kpc, as measured in Bovy et al. (2012), and get a progenitor mass of 2.3 × 104 M , very similar to that reported in Küpper et al. (2015).”