The local dark matter density

By Justin I. Read. 2014

318 citations recorded by the source corpus.

I review current efforts to measure the mean density of dark matter near the Sun. This encodes valuable dynamical information about our Galaxy and is also of great importance for ?direct detection? dark matter experiments. I discuss theoretical expectations in our current cosmology; the theory behind mass modelling of the Galaxy; and I show how combining local and global measures probes the shape of the Milky Way dark matter halo and the possible presence of a ?dark disc?. I stress the strengths and weaknesses of different methodologies and highlight the continuing need for detailed tests on mock data?particularly in the light of recently discovered evidence for disequilibria in the Milky Way disc. I collate the latest measurements of ?dm and show that, once the baryonic surface density contribution ?b is normalized across different groups, there is remarkably good agreement. Compiling data from the literature, I estimate ?b = 54.2 ? 4.9?M?pc?2, where the dominant source of uncertainty is in the H?i gas contribution. Assuming this contribution from the baryons, I highlight several recent measurements of ?dm in order of increasing data complexity and prior, and, correspondingly, decreasing formal error bars. Comparing these measurements with spherical extrapolations from the Milky Way?s rotation curve, I show that the Milky Way is consistent with having a spherical dark matter halo at R0 ? 8 kpc. The very latest measures of ?dm based on ?10?000 stars from the Sloan Digital Sky Survey appear to favour little halo flattening at R0, suggesting that the Galaxy has a rather weak dark matter disc, with a correspondingly quiescent merger history. I caution, however, that this result hinges on there being no large systematics that remain to be uncovered in the SDSS data, and on the local baryonic surface density being ?b ? 55?M?pc?2. I conclude by discussing how the new Gaia satellite will be transformative. We will obtain much tighter constraints on both ?b and ?dm by having accurate 6D phase space data for millions of stars near the Sun. These data will drive us towards fully three dimensional models of our Galactic potential, moving us into the realm of precision measurements of??dm.

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

View Paper: https://www.semanticscholar.org/paper/556730c204e2da6675f7d79b4c3a55a31c6e9007

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Citations in the corpus

History of dark matter (2018, unknown): “We refer the interested reader to the review by Read (2014) for further details and references.”
On the estimation of the local dark matter density using the rotation curve of the Milky Way (2019, methodology): “For a comprehensive review of the rotation curve’s method and other methods to infer ρDM, we refer the reader to [2].”
Dynamical modelling of the galactic bulge and bar: the Milky Way's pattern speed, stellar and dark matter mass distribution (2016, background): “In addition, the dark matter contribution to the radial force increases with galactocentric radius reaching about 50% at the solar radius (Read 2014).”
The mass distribution and gravitational potential of the Milky Way (2016, background): “In the Solar neighbourhood,Read(2014) noted that the comparison of constraints from the rotation curve (which providesan estimate of the spherically averaged enclosed dark-matter content) and estimates of the local density provide a constraint on the halo shape which is consistent with spherical or…”
Small-Scale Challenges to the ΛCDM Paradigm (2017, background): “1 Mpc at densities characteristic of the Milky Way’s dark matter halo (0.4 Gev/cm3; Read 2014), leading to self-interaction cross sections of 400 & σ/m & 0.4 cm2/g (800 & σ/m & 0.8 barn/GeV).”
The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, methodology): “In the Milky Way, constraints on the shape of the dark halo are based on the Sgr orbit, tidal streams, SDSS kinematics, flaring of the HI layer, and combining rotation curve and vertical acceleration measurements (see the review by Read 2014).”
Dark Matter through the Higgs portal (2019, unknown): “[279–288] for more details.”