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We have compiled a new sample of 240 halo objects with accurate distance and radial velocity measurements, including globular clusters, satellite galaxies, field blue horizontal branch stars and red giant stars from the Spaghetti survey.…

A simple model for the Milky Way halo is presented. It has a flat rotation curve in the inner regions, but the density falls off sharply beyond an outer edge. This truncated, flat rotation curve (TF) model possesses a rich family of simple…

Astrophysics · Physics 2008-11-26 M. I. Wilkinson , N. W. Evans

A family of spherical halo models with flat circular velocity curves is presented. This includes models in which the rotation curve has a finite central value but declines outwards (like the Jaffe model). It includes models in which the…

Astrophysics of Galaxies · Physics 2015-06-24 N. W. Evans , J. An , A. Bowden , A. A. Williams

We introduce the flattening equation, which relates the shape of the dark halo to the angular velocity dispersions and the density of a tracer population of stars. It assumes spherical alignment of the velocity dispersion tensor, as seen in…

Astrophysics of Galaxies · Physics 2016-05-25 A. Bowden , N. W. Evans , A. A. Williams

We develop a flexible set of action-based distribution functions (DFs) for stellar haloes. The DFs have five free parameters, controlling the inner and outer density slope, break radius, flattening and anisotropy respectively. The DFs…

Astrophysics of Galaxies · Physics 2015-09-30 A. A. Williams , N. W. Evans

We re-analyse the velocity-dispersion profile sigma(r) at radii r>10 kpc in the Galactic stellar halo, recently derived by Battaglia et al. (2005), who concluded that, for constant velocity anisotropy of the tracers, these data rule out a…

Astrophysics · Physics 2009-11-11 Walter Dehnen , Dean McLaughlin , Jalpesh Sachania

We characterise the radial density, metallicity and flattening profile of the Milky Way's stellar halo, based on the large sample of 1757 spectroscopically confirmed giant stars from SDSS/SEGUE-2 after excising stars that were…

Astrophysics of Galaxies · Physics 2015-08-26 Xiang-Xiang Xue , Hans-Walter Rix , Zhibo Ma , Heather Morrison , Jo Bovy , Branimir Sesar , William Janesh

We use high-quality optical rotation curves of 9 low-luminosity disk galaxies to obtain the velocity profile of the surrounding dark matter halos. We find that they increase linearly with radius at least out to the stellar disk edge,…

Astrophysics · Physics 2009-10-31 A. Borriello , P. Salucci

Cosmological N--body simulations have revealed a remarkable similarity in the structure of dark matter halos formed in hierarchically clustering universes. Regardless of halo mass, cosmological parameters, and power spectrum of initial…

Astrophysics · Physics 2007-05-23 Julio F. Navarro

Halo stars orbit within the potential of the Milky Way and hence their kinematics can be used to understand the underlying mass distribution. However, the inferred mass distribution depends sensitively upon assumptions made on the density…

Astrophysics of Galaxies · Physics 2015-06-22 Prajwal R. Kafle , Sanjib Sharma , Geraint F. Lewis , Joss Bland-Hawthorn

We present a set of highly flattened galaxy models with asymptotically constant rotation curves. The mass density in the equatorial plane falls like (distance)$^{-1}$ at large radii. Although the inner equidensity contours may be spherical,…

Astrophysics of Galaxies · Physics 2015-06-22 N. W. Evans , A. Bowden

Dynamical properties of two-component galaxy models whose stellar density distribution is described by a gamma-model while the total density distribution has a pure r^(-2) profile, are presented. The orbital structure of the stellar…

Astrophysics · Physics 2009-11-13 Luca Ciotti , Lucia Morganti , Tim de Zeeuw

We use distant Blue Horizontal Branch stars with Galactocentric distances 16 < r/kpc < 48 as kinematic tracers of the Milky Way dark halo. We model the tracer density as an oblate, power-law embedded within a spherical power-law potential.…

Astrophysics of Galaxies · Physics 2015-06-04 A. J. Deason , V. Belokurov , N. W. Evans , J. H. An

We study the mass, velocity dispersion, and anisotropy profiles of $\Lambda$CDM halos using a suite of N-body simulations of unprecedented numerical resolution (the {\it Aquarius Project}). Our analysis confirms a number of results claimed…

We construct a new family of models of our Galaxy in which dark matter and disc stars are both represented by distribution functions that are analytic functions of the action integrals of motion. The potential that is self-consistently…

Astrophysics of Galaxies · Physics 2016-12-14 David R. Cole , James Binney

The radial number density and flattening of the Milky Way's stellar halo is measured with $\mathrm{5351}$ metal-poor ([Fe/H]$<-1$) K giants from LAMOST DR3, using a nonparametric method which is model independent and largely avoids the…

We present a new method to construct fully self-consistent equilibrium models of multi-component disc galaxies similar to the Milky Way. We define distribution functions for the stellar disc and dark halo that depend on phase space position…

Astrophysics of Galaxies · Physics 2015-07-03 T. Piffl , Z. Penoyre , J. Binney

We develop a self-consistent and accurate halo model by partitioning matter according to the depletion radii of haloes. Unlike conventional models that define haloes with the virial radius while relying on a separate exclusion radius or…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-20 Yifeng Zhou , Jiaxin Han

We use N-body simulations to investigate the structure of dark halos in the standard Cold Dark Matter cosmogony. Halos are excised from simulations of cosmologically representative regions and are resimulated individually at high…

Astrophysics · Physics 2008-11-26 Julio F. Navarro , Carlos S. Frenk , Simon D. M. White

We present the 21-cm rotation curve of the nearby galaxy M33 out to a galactocentric distance of 16 kpc (13 disk scale-lengths). The rotation curve keeps rising out to the last measured point and implies a dark halo mass larger than 5…

Astrophysics · Physics 2009-10-31 Edvige Corbelli , Paolo Salucci
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