A new determination of the local dark matter density from the kinematics of K dwarfs

By S. Garbari, Chao Liu, Justin I. Read, George Lake. 2012

135 citations recorded by the source corpus.

We apply a new method to determine the local disc matter and dark halo matter density to kinematic and position data for ˜2000 K dwarf stars taken from the literature. Our method assumes only that the disc is locally in dynamical equilibrium, and that the 'tilt' term in the Jeans equations is small up to ˜1 kpc above the plane. We present a new calculation of the photometric distances to the K dwarf stars, and use a Monte Carlo Markov chain to marginalize over uncertainties in both the baryonic mass distribution, and the velocity and distance errors for each individual star. We perform a series of tests to demonstrate that our results are insensitive to plausible systematic errors in our distance calibration, and we show that our method recovers the correct answer from a dynamically evolved N-body simulation of the Milky Way. We find a local dark matter density of ρ dm =0.025-0.013+0.014 Msun pc-3 (0.95-0.49+0.53 GeV cm-3) at 90 per cent confidence assuming no correction for the non-flatness of the local rotation curve, and ρ dm =0.022-0.013+0.015 Msun pc-3 (0.85-0.50+0.57 GeV cm-3) if the correction is included. Our 90 per cent lower bound on ρdm is larger than the canonical value typically assumed in the literature, and is at mild tension with extrapolations from the rotation curve that assume a spherical halo. Our result can be explained by a larger normalization for the local Milky Way rotation curve, an oblate dark matter halo, a local disc of dark matter or some combination of these.

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

Constraining the Galaxy's dark halo with RAVE stars (2014, background): “However, Garbari et al. (2012) showed by analysing mock data sets from N-body simulations that this can bias the results to lower values.”
Gamma Ray Signals from Dark Matter: Concepts, Status and Prospects (2012, background): “[73] for a recent study that includes the effect of a slightly oblate DM halo and the possible presence of a dark disc, leading to a normalization which is a factor of ∼2-3 larger).”
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): “…of the local surface density to 1.1 kpc is consistent with all previous measurements (which are really KZ,1.1(R0) measurements) but with a smaller uncertainty (Kuijken & Gilmore 1989b; Siebert et al. 2003; Holmberg & Flynn 2004; Bienaymé et al. 2006; Garbari et al. 2012; Zhang et al. 2013).”
Numerical simulations of the dark universe: State of the art and the next decade (2012, unknown): “85 GeV cm−3 [151–154].”
The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, background): “Near the Sun, the local shape of the dark matter halo is constrained by the ratio of the local dark matter density to the average enclosed spherical dark matter density (Garbari et al. 2012, Read 2014).”
The mass distribution and gravitational potential of the Milky Way (2016, background): “The value we find (0.0100± 0.0010 M⊙ pc−3) is larger than many of the local measures in the compilation (though not all, e.g.,Garbari et al. 2012, when no strong prior on the baryonic component is invoked).”
The local dark matter density (2014, methodology): “A second possibility for detecting the ‘dark disc’ is via its dynamical influence – i.e. its contribution to ρdm (Read et al., 2008; Garbari et al., 2012).”
Galactic Searches for Dark Matter (2012, methodology): “Kuijken and Gilmore (1989b) utilized a sample of approximately 2000 K giant stars; the distances for this sample were re-calibrated by Garbari et al. (2012) in a more recent analysis.”
STARS, GAS, AND DARK MATTER IN THE SOLAR NEIGHBORHOOD (2015, methodology): “In addition, we have omitted Garbari et al. (2012), since Read (2014) has shown that the total surface density of matter inferred by their method is very sensitive7 to bS .”
Galaxy Masses: A Review (2013, methodology): “We note that Gavazzi et al. (2007) used a combination of strong and weak lensing measurements around massive ellipticals and found that a SIS model provides a good fit to the data.”
The Milky Way’s stellar disk (2013, background): “Garbari et al. (2012) reanalyzed literature data, but properly marginalized over a number of assumptions and parameters in previous analyses, and inferred ρDM = 0.025 +0.013 −0.014M⊙ pc −3, potentially indicating a flattened halo.”