Gaussian Processes, Median Statistics, Milky Way Rotation Curves

Abstract

We use the Iocco et al. (2015) compilation of 2,780 circular velocity measurements to analyze the Milky Way rotation curve. We find that the error bars for individual measurements are non-gaussian, and hence instead derive median statistics binned central circular velocity values and error bars from these data. We use these median statistics central values and error bars to fit the data to simple, few parameter, rotation curve functions. These simple functions are unable to adequately capture the significant small scale spatial structure in these data and so provide poor fits. We introduce and use the Gaussian Processes (GP) method to capture this small scale structure and use it to derive Milky Way rotation curves from the binned median statistics circular velocity data. The GP method rotation curves have significant small-scale spatial structure superimposed on a broad rise to galactocentric radius $R\approx 7$ kpc and a decline at larger $R$. We use the GP method median statistics rotation curve to measure the Oort $A$ and $B$ constants and other characteristic rotation curve quantities. We study correlations in the residual circular velocities (relative to the GP method rotation curve). Along with other evidence for azimuthal asymmetry of the Milky Way circular rotation velocity field, we find that larger residual circular velocities seem to favor parts of spiral arms.

arXiv comment37 pages, 32 figures. Comments are welcome

References in corpus (53)

• emcee: The MCMC Hammer
• Planck 2015 results. XIII. Cosmological parameters
• The VizieR database of Astronomical Catalogues
• Trigonometric Parallaxes of High Mass Star Forming Regions: the Structure and Kinematics of the Milky Way
• A 6% measurement of the Hubble parameter at $z\sim 0.45$: direct evidence of the epoch of cosmic re-acceleration
• A New Era in the Quest for Dark Matter
• Planck 2015 results. XVII. Constraints on primordial non-Gaussianity
• Reconstruction of dark energy and expansion dynamics using Gaussian processes
• Hubble parameter measurement constraints on the cosmological deceleration-acceleration transition redshift
• Hubble parameter measurement constraints on the redshift of the deceleration-acceleration transition, dynamical dark energy, and space curvature
• Galactic Kinematics of Cepheids from Hipparcos Proper Motions
• Hubble Parameter and Baryon Acoustic Oscillation Measurement Constraints on the Hubble Constant, the Deviation from the Spatially-Flat $\Lambda$cdm Model, The Deceleration-Acceleration Transition Redshift, and Spatial Curvature
• Unified Rotation Curve of the Galaxy -- Decomposition into de Vaucouleurs Bulge, Disk, Dark Halo, and the 9-kpc Rotation Dip --
• Gaussian Process Cosmography
• Nonparametric Dark Energy Reconstruction from Supernova Data
• Median Statistics, H_0, and the Accelerating Universe
• Clustering of Local Group distances: publication bias or correlated measurements? I. The Large Magellanic Cloud
• Evidence for dark matter in the inner Milky Way
• Dynamical constraints on the dark matter distribution in the Milky Way
• Nonparametric Reconstruction of the Dark Energy Equation of State
• Median statistics and the Hubble constant
• Null test of the cosmic curvature using $H(z)$ and supernovae data
• Galactic rotation in Gaia DR1
• Milky Way Kinematics: Measurements at the Subcentral Point of the Fourth Quadrant
• Using H(z) data as a probe of the concordance model
• Nonparametric Reconstruction of the Dark Energy Equation of State from Diverse Data Sets
• Simulated Milky Way analogues: implications for dark matter direct searches
• The Beginning and Evolution of the Universe
• Non-Gaussian Error Distribution of Hubble Constant Measurements
• Planck 2015 constraints on the non-flat $\Lambda$CDM inflation model
• The power spectrum of the Milky Way: Velocity fluctuations in the Galactic disk
• Simulated Milky Way analogues: implications for dark matter indirect searches
• Rotation and Mass in the Milky Way and Spiral Galaxies
• New Model-independent Method to Test the Curvature of the Universe
• We do not live in the R_h = c t universe
• Hubble parameter data constraints on dark energy
• Clustering of Local Group distances: publication bias or correlated measurements? IV. The Galactic Center
• Gaussianity of Degree-Scale Cosmic Microwave Background Anisotropy Observations
• Measuring the cosmic proper distance from fast radio bursts
• Not Normal: the uncertainties of scientific measurements
• Median Statistics Estimate of the Distance to the Galactic Center
• The Mass Distribution and Rotation Curve in the Galaxy
• The primordial deuterium abundance at z = 2.504 from a high signal-to-noise spectrum of Q1009+2956
• Model-independent Constraints on Cosmic Curvature and Opacity
• The dark matter profile of the Milky Way: a non-parametric reconstruction
• $\text{galkin}$: a new compilation of the Milky Way rotation curve data
• Clustering of Local Group distances: publication bias or correlated measurements? V. Galactic rotation constants
• Non-Gaussian Error Distributions of LMC Distance Moduli Measurements
• Non-Gaussian Error Distribution of ${}^7\mathrm{Li}$ Abundance Measurements
• Milky Way Kinematics. II. A uniform inner Galaxy HI terminal velocity curve
• Median Statistics Analysis of Deuterium Abundance Measurements and Spatial Curvature Constraints
• The local rotation curve of the Milky Way based on SEGUE and RAVE data
• Non-Gaussian Error Distributions of Galactic Rotation Speed Measurements

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