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(Abridged) Axisymmetric models of the Milky Way exhibit strong interrelations between the Galactic constants (R_0 and T_0), the stellar columndensity (S_*) and the shape of the dark matter (DM) halo. Here we present analytical relations…

Astrophysics · Physics 2009-11-06 R. P. Olling , M. R. Merrifield

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 derive the mass model of the Milky Way (MW) using a cored dark matter (DM) halo profile and recent data. The method used consists in fitting a spherically symmetric model of the Galaxy with a Burkert DM halo profile to available data: MW…

Astrophysics of Galaxies · Physics 2015-06-15 Fabrizio Nesti , Paolo Salucci

Understanding the formation and evolutionary history of the Milky Way requires detailed mapping of its stellar components, which preserve fossil records of the Galaxy's assembly through cosmic time. RR Lyrae stars are particularly…

Astrophysics of Galaxies · Physics 2026-03-19 Madeline Lucey , Cecilia Mateu , Adrian Price-Whelan , David Hogg , Hans-Walter Rix , Robyn Sanderson

We exploit the first \gaia data release to study the properties of the Galactic stellar halo as traced by RR Lyrae. We demonstrate that it is possible to select a pure sample of RR Lyrae using only photometric information available in the…

Astrophysics of Galaxies · Physics 2017-12-27 G. Iorio , V. Belokurov , D. Erkal , S. E. Koposov , C. Nipoti , F. Fraternali

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

In this work we characterize the distribution of Dark Matter (DM) in the Milky Way (MW), and its uncertainties, adopting the well known "Rotation Curve" method. We perform a full marginalization over the uncertainties of the Galactic…

Astrophysics of Galaxies · Physics 2019-06-12 Maria Benito , Alessandro Cuoco , Fabio Iocco

The rotation curve, the total mass and the gravitational potential of the Galaxy are sensitive measurements of the dark matter halo profile. In this publication cuspy and cored DM halo profiles are analysed with respect to recent…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-30 Markus Weber , Wim de Boer

We explore the density profile, shape, and virial mass of the Milky Way's dark matter halo using K giants (KG) from LAMOST and SDSS/SEGUE, as well as blue horizontal branch (BHB) stars from SDSS. Incorporating Gaia DR3 proper motions, we…

Astrophysics of Galaxies · Physics 2025-05-15 Lan Zhang , Xiang-Xiang Xue , Ling Zhu , Ruizhi Zhang , Chengqun Yang , Shi Shao , Jiang Chang , Feilu Wang , Hao Tian , Gang Zhao , Chao Liu

We use ESA/Gaia astrometry together with SEGUE and LAMOST measurements of the GD-1 stellar stream to explore the improvement on the Galactic gravitational potential that these new data provide. Assuming a realistic universal model for the…

Astrophysics of Galaxies · Physics 2019-04-24 Khyati Malhan , Rodrigo A. Ibata

A seven-parameter distribution function (DF) is fitted to $20\,000$ RR-Lyrae stars for which only astrometric data are available. The observational data are predicted by the DF in conjunction with the gravitational potential of a…

Astrophysics of Galaxies · Physics 2022-01-05 Chengdong Li , James Binney

We constrain the shape of the Milky Way's halo by dynamical modeling of the observed phase-space tracks of the Pal 5 and GD-1 tidal streams. We find that the only information about the potential gleaned from the tracks of these streams are…

Astrophysics of Galaxies · Physics 2017-02-10 Jo Bovy , Anita Bahmanyar , Tobias K. Fritz , Nitya Kallivayalil

We probe the gravitational force perpendicular to the Galactic plane at the position of the Sun based on a sample of red giants, with measurements taken from the DR3 Gaia catalogue. Measurements far out of the Galactic plane up to 3.5 kpc…

Astrophysics of Galaxies · Physics 2024-07-02 O. Bienaymé , A. C. Robin , J. -B. Salomon , C. Reylé

We estimated the dynamical surface mass density Sigma at the solar position between Z=1.5 and 4 kpc from the Galactic plane, as inferred from the kinematics of thick disk stars. The formulation is exact within the limit of validity of a few…

Astrophysics of Galaxies · Physics 2015-06-04 C. Moni Bidin , G. Carraro , R. A. Mendez , R. Smith

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

Our current understanding of how dark matter (DM) is distributed within the Milky Way halo, particularly in the solar neighborhood, is based on either careful studies of the local stellar orbits, model assumptions on the global shape of the…

The distribution of shapes of galaxies' dark halos provides a basic test for models of galaxy formation. To-date, few dark halo shapes have been measured, and the results of different methods appear contradictory. Here, we add to the sample…

Astrophysics · Physics 2007-05-23 R. P. Olling , M. R. Merrifield

A recently discovered young, high-velocity giant star J01020100-7122208 is a good candidate of hypervelocity star ejected from the Galactic center, although it has a bound orbit. If we assume that this star was ejected from the Galactic…

Astrophysics of Galaxies · Physics 2020-05-20 Kohei Hattori , Monica Valluri

The structure, extent, and mass of the Milky Way's (MW) dark matter (DM) halo are observationally challenging to determine due to our position within the Galaxy. To overcome this limitation, we study a combined sample of 127 MW analogs from…

We estimate the mass of the inner ($<20$ kpc) Milky Way and the axis ratio of its dark matter halo using globular clusters as tracers. At the same time, we constrain the phase-space distribution of the globular cluster system. We use the…

Astrophysics of Galaxies · Physics 2019-01-09 Lorenzo Posti , Amina Helmi
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