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We present a percent-level accurate model of the line-of-sight velocity distribution of galaxies around dark matter halos as a function of projected radius and halo mass. The model is developed and tested using synthetic galaxy catalogs…

Cosmology and Nongalactic Astrophysics · Physics 2023-04-05 Han Aung , Daisuke Nagai , Eduardo Rozo , Brandon Wolfe , Susmita Adhikari

This article reports a measurement of the proper motion of Leo II, a dwarf galaxy that is a likely satellite of the Milky Way, based on imaging with the Hubble Space Telescope and Wide Field Camera 3. The measurement uses compact background…

Astrophysics of Galaxies · Physics 2016-11-23 Slawomir Piatek , Carlton Pryor , Edward W. Olszewski

We use FIRE-2 zoom simulations of Milky Way size disk galaxies to derive easy-to-use relationships between the observed circular speed of the Galaxy at the Solar location, $v_\mathrm{c}$, and dark matter properties of relevance for direct…

Astrophysics of Galaxies · Physics 2024-08-15 Patrick G. Staudt , James S. Bullock , Michael Boylan-Kolchin , David Kirkby , Andrew Wetzel , Xiaowei Ou

We introduce a comprehensive analysis of multi-epoch stellar line-of-sight velocities to determine the intrinsic velocity dispersion of the ultrafaint satellites of the Milky Way. Our method includes a simultaneous Bayesian analysis of both…

Astrophysics of Galaxies · Physics 2011-08-17 Gregory D. Martinez , Quinn E. Minor , James Bullock , Manoj Kaplinghat , Joshua D. Simon , Marla Geha

We present results from spectroscopic observations with the Michigan/Magellan Fiber System (M2FS) of 182 stellar targets along the line of sight to the newly-discovered `ultrafaint' object Reticulum 2 (Ret 2). For 38 of these targets, the…

We use a particle tagging technique to dynamically populate the N-body Via Lactea II high-resolution simulation with stars. The method is calibrated using the observed luminosity function of Milky Way satellites and the concentration of…

Astrophysics of Galaxies · Physics 2015-05-28 Valery Rashkov , Piero Madau , Michael Kuhlen , Jurg Diemand

We report the discovery of a new, low luminosity star cluster in the outer halo of the Milky Way. High quality $gr$ photometry is presented, from which a color-magnitude diagram is constructed, and estimates of age, [Fe/H], [$\alpha$/Fe],…

Astrophysics of Galaxies · Physics 2015-06-23 Dongwon Kim , Helmut Jerjen , Antonino P. Milone , Dougal Mackey , Gary S. Da Costa

We present the results of a pilot project designed to study the distribution of dark matter haloes out to very large radii in spiral galaxies. As dynamical probe we use their rotation curves and the motions population of satellite galaxies.…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 I. A. Yegorova , A. Pizzella , P. Salucci

We use the recently completed one billion particle Via Lactea II LambdaCDM simulation to investigate local properties like density, mean velocity, velocity dispersion, anisotropy, orientation and shape of the velocity dispersion ellipsoid,…

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 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 examine the claim by Oppenheimer et al. (2001) that the local halo density of white dwarfs is an order of magnitude higher than previously thought. As it stands, the observational data support the presence of a kinematically distinct…

Astrophysics · Physics 2017-08-23 L. V. E. Koopmans , R. D. Blandford

The Milky Way has a large population of dwarf galaxy satellites. Their properties are sensitive to both cosmology and the physical processes underlying galaxy formation, but these properties are still not properly characterized for the…

Using the first 25% of DEEP2 Redshift Survey data, we probe the line-of-sight velocity dispersion profile for isolated galaxies with absolute B-band magnitude -22<M_B-5log(h)<-21 at z=0.7-1.0, using satellite galaxies as luminous tracers of…

We present radial velocity and metallicity measurements for the far-southern Galactic globular cluster IC4499. We selected several hundred target red giant stars in and around the cluster from the 2MASS point source catalog, and obtained…

Astrophysics of Galaxies · Physics 2010-11-17 Warren J. Hankey , Andrew A. Cole

We investigate the spatial distribution, kinematics, and metallicity of stars in the Draco dwarf spheroidal galaxy using data from the Dark Energy Spectroscopic Instrument (DESI). We identify 155 high probability members of Draco using line…

The proper motions of stars in the outskirts of globular clusters are used to estimate cluster velocity dispersion profiles as far as possible within their tidal radii. We use individual color-magnitude diagrams to select high probability…

Astrophysics of Galaxies · Physics 2021-12-08 Raymond G. Carlberg , Carl J. Grillmair

We present the first clear evidence for an extended dark matter halo in the Draco dwarf spheroidal galaxy based on a sample of new radial velocities for 159 giant stars out to large projected radii. Using a two parameter family of halo…

Astrophysics · Physics 2009-11-07 Jan T. Kleyna , Mark I. Wilkinson , N. Wyn Evans , Gerard Gilmore

We examine the amplitude of the rotation velocity that can be attributed to the dark matter halos of disk galaxies, focusing on well measured intermediate radii. The data for 60 galaxies spanning a large range of mass and Hubble types,…

Astrophysics · Physics 2010-11-05 S. S. McGaugh , W. J. G. de Blok , J. M. Schombert , R. Kuzio de Naray , J. H. Kim

We measure the three components of velocity dispersion, $\sigma_{R},\sigma_{\theta},\sigma_{\phi}$, for stars within 6 < R < 30 kpc of the Milky Way using a new radial velocity sample from the MMT telescope. We combine our measurements with…

Astrophysics of Galaxies · Physics 2015-11-11 Charles King , Warren R. Brown , Margaret J. Geller , Scott J. Kenyon