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The existence of the cosmic ray Halo in our Galaxy has been discussed for more than half a century. If it is real it could help to explain some puzzling features of the cosmic ray flux: its small radial gradient, nearly perfect isotropy and…

Astrophysics of Galaxies · Physics 2015-06-19 Anatoly Erlykin , Arnold Wolfendale

We have mapped the number density and mean vertical velocity of the Milky Way's stellar disk out to roughly two kiloparsecs from the Sun using Gaia Data Release 3 (DR3) and complementary photo-astrometric distance information from…

Astrophysics of Galaxies · Physics 2022-12-14 Axel Widmark , Lawrence M. Widrow , Aneesh Naik

Dynamos in astrophysical disks are usually explained in terms of the standard alpha-omega mean field dynamo model where the local helicity generates a radial field component from an azimuthal field. The subsequent shearing of the radial…

Astrophysics · Physics 2015-06-24 Ethan T. Vishniac

We study the dynamical properties of spherical galaxies with surface luminosity profile described by the R^{1/m}-law, in which a variable degree of orbital anisotropy is allowed. The parameter m for the present models covers the range…

Astrophysics · Physics 2007-05-23 L. Ciotti , B. Lanzoni

In this paper, we investigate some chemokinematical properties of the Milky Way disk, by using a sample composed by 424 late-type dwarfs. We show that the velocity dispersion of a stellar group correlates with the age of this group,…

Astrophysics · Physics 2009-11-10 H. J. Rocha-Pinto , C. Flynn , J. Scalo , J. Hanninen , W. J. Maciel , G. Hensler

We present a 2D kinematic analysis out to ~2-5 effective radii (Re) of 33 massive elliptical galaxies with stellar velocity dispersions larger than 150 km/s. Our observations were taken using the Mitchell Spectrograph (formerly VIRUS-P), a…

Astrophysics of Galaxies · Physics 2015-06-19 Sudhir Raskutti , Jenny Greene , Jeremy Murphy

We present the line-of-sight (LOS) velocities for 13 distant main sequence Milky Way halo stars with published proper motions. The proper motions were measured using long baseline (5-7 years) multi-epoch HST/ACS photometry, and the LOS…

A growing body of observational evidence suggests that the luminosity, photometric shape and amount of rotational or anisotropical support in elliptical galaxies may provide vital clues to how they formed. Elliptical galaxies appear to fall…

Astrophysics · Physics 2008-11-26 B. Rothberg , R. D. Joseph

Approximately half of all disc galaxies exhibit appreciable warps in both their stellar and HI discs. The typical warp amplitude is small (a few degrees), and only becomes noticeable at the periphery of the galaxy disc. As a result, warps…

We apply four different mass modelling methods to a suite of publicly available mock data for spherical stellar systems. We focus on the recovery of the density and velocity anisotropy as a function of radius, using either line-of-sight…

Astrophysics of Galaxies · Physics 2020-12-02 J. I. Read , G. A. Mamon , E. Vasiliev , L. L. Watkins , M. G. Walker , J. Penarrubia , M. Wilkinson , W. Dehnen , P. Das

Here we study the metallicity bias in the velocity dispersions, the derived quantity called anisotropy and the mean azimuthal velocity profiles of the Milky Way stellar halo using Blue Horizontal Branch (BHB) stars taken from SDSS/SEGUE…

Astrophysics of Galaxies · Physics 2013-02-18 P. R. Kafle , S. Sharma , G. F. Lewis , J. Bland-Hawthorn

We investigate the anisotropy of the stellar velocity dispersions within the effective radius, $R_{\rm e}$, in 24 ATLAS$^{\rm 3D}$ pure-bulge galaxies, 16 of which are kinematic slow rotators (SRs). We allow the spherical anisotropy…

Astrophysics of Galaxies · Physics 2019-04-03 Kyu-Hyun Chae , Mariangela Bernardi , Ravi K. Sheth

We use the second Gaia data release in combination with the catalog of Sanders & Das (2018) to dissect the Milky Way disc in phase-space and relative ages. We confirm and report the existence of multiple velocity moving groups at low…

Astrophysics of Galaxies · Physics 2020-10-28 Chervin F. P. Laporte , Benoit Famaey , Giacomo Monari , Vanessa Hill , Christopher Wegg , Ortwin Gerhard

A suite of vast stellar surveys mapping the Milky Way, culminating in the Gaia mission, is revolutionizing the empirical information about the distribution and properties of stars in the Galactic stellar disk. We review and lay out what…

Astrophysics of Galaxies · Physics 2013-12-04 Hans-Walter Rix , Jo Bovy

The use of the tensor virial theorem (TVT) as a diagnostic of anisotropic velocity distributions in galaxies is revisited. The TVT provides a rigorous global link between velocity anisotropy, rotation and shape, but the quantities appearing…

Astrophysics · Physics 2009-11-11 James Binney

We analyze radial stellar metallicity and kinematic profiles out to 1Re in 244 CALIFA galaxies ranging from morphological type E to Sd, to study the evolutionary mechanisms of stellar population gradients. We find that linear metallicity…

In the context of the study of the properties of the mutual mass distribution of the bright and dark matter in elliptical galaxies, present a family of two-component, spherical, self-consistent galaxy models, where one density distribution…

Astrophysics · Physics 2009-10-31 L. Ciotti

We validate the Bond et al. (2010) kinematic models for the Milky Way's disk and halo stars with Gaia Data Release 3 data. Bond et al. constructed models for stellar velocity distributions using stellar radial velocities measured by the…

Astrophysics of Galaxies · Physics 2024-09-02 Bruno Domínguez , Siddharth Chaini , Karlo Mrakovčić , Brandon Sallee , Željko Ivezić

We analyse the orbital distribution of E and S0 galaxies using SAURON integral-field stellar kinematics. We construct the anisotropy (V/sigma,epsilon) diagram, for the 48 E/S0 galaxies from the SAURON survey. For a subsample of 24 galaxies…

Stars near the Sun oscillate both horizontally and vertically. In Paper I the coupling between these motions was modelled by determining the horizontal motion without reference to the vertical motion, and recovering the coupling by assuming…

Astrophysics of Galaxies · Physics 2015-05-20 James Binney , Paul McMillan