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We obtain predictions for the properties of cold dark matter annihilation radiation using high resolution hydrodynamic zoom-in cosmological simulations of Milky Way-like galaxies (APOSTLE project) carried out as part of the "Evolution and…

We have compiled a sample of 699 stars from the recent literature with detailed chemical abundance information (spanning -4.2 < [Fe/H] < +0.3), and we compute their space velocities and Galactic orbital parameters. We identify members of…

Astrophysics · Physics 2009-11-13 Ian U. Roederer

The stars within our Galactic halo presents a snapshot of its ongoing growth and evolution, probing galaxy formation directly. Here, we present our first analysis of the stellar halo from detailed maps of Blue Horizontal Branch (BHB) stars…

Astrophysics of Galaxies · Physics 2018-08-01 Zhen Wan , Prajwal R. Kafle , Geraint F. Lewis , Dougal Mackey , Sanjib Sharma , Rodrigo A. Ibata

Using the Hubble Space Telescope, we have resolved individual red-giant branch stars in the halos of eight nearby spiral galaxies. The fields lie at projected distances between 2 and 13 kpc along the galaxies' minor axes. The data set…

Astrophysics · Physics 2009-11-13 M. Mouhcine , H. C. Ferguson , R. M. Rich , T. M. Brown , T. E. Smith

We measure the orbital properties of halo stars using 7-dimensional information provided by Gaia and the Sloan Digital Sky Survey. A metal-rich population of stars, present in both local main sequence stars and more distant blue horizontal…

Astrophysics of Galaxies · Physics 2018-08-01 Alis J. Deason , Vasily Belokurov , Sergey E. Koposov , Lachlan Lancaster

CONTEXT. The maximum size of the Galactic stellar disk is not yet known. Some studies have suggested an abrupt drop-off of the stellar density of the disk at Galactocentric distances $R\gtrsim 15$ kpc, which means that in practice no disk…

Astrophysics of Galaxies · Physics 2018-05-09 M. Lopez-Corredoira , C. Allende Prieto , F. Garzon , H. Wang , C. Liu , L. Deng

The formation mechanism of the hot gaseous halo associated with the Milky Way Galaxy is still under debate. We report new observational constraints on the gaseous halo using 107 lines-of-sight of the Suzaku X-ray observations at…

Astrophysics of Galaxies · Physics 2018-08-08 Shinya Nakashima , Yoshiyuki Inoue , Noriko Yamasaki , Yoshiaki Sofue , Jun Kataoka , Kazuhiro Sakai

We present a search for RR Lyrae variable stars from archival observations of the Southern Edgeworth-Kuiper Belt Object survey. The survey covers 1675 square degrees along the ecliptic to a mean depth of V=19.5, i.e. a heliocentric distance…

Astrophysics · Physics 2009-11-13 Stefan C. Keller , Simon Murphy , Sayuri Prior , Gary DaCosta , Brian Schmidt

We have combined observations of Galactic high-velocity HI from two surveys: a very sensitive survey from the Green Bank 140ft Telescope with limited sky coverage, and the less sensitive but complete Galactic All Sky Survey from the 64m…

Astrophysics of Galaxies · Physics 2017-01-18 Vanessa A. Moss , Felix J. Lockman , Naomi M. McClure-Griffiths

We predict that there is a population of low-luminosity dwarf galaxies orbiting within the halo of the Milky Way that have surface brightnesses low enough to have escaped detection in star-count surveys. The overall count of stealth…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 James S. Bullock , Kyle R. Stewart , Manoj Kaplinghat , Erik J. Tollerud , Joe Wolf

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…

We report the detection of a 282 $^{+34}_{-31}$ pc-sized core in the center of Milky Way dark matter halo at $68\%$ confidence level by using the micro-lensing event rate sky map data from the Optical Gravitational Lensing Experiment (OGLE)…

Astrophysics of Galaxies · Physics 2025-01-16 Shu-Rui Lin , Wentao Luo , Yi-Fu Cai , Qi Guo , Leyao Wei , Bo Wang , Qinxun Li , Can-Po Su , Alexander Rodriguez

RR Lyrae stars are standard candles with characteristic photometric variability and serve as powerful tracers of Galactic structure, substructure, accretion history, and dark matter content. Here we report the discovery of distant RR Lyrae…

(Abridged) We perform an analysis of spectra and photometry for 22,770 stars included in the third data release (DR3) of the SDSS. We measure radial velocities and, based on a model-atmosphere analysis, derive estimates ofthe atmospheric…

Astrophysics · Physics 2009-09-29 C. Allende Prieto , T. C. Beers , R. Wilhelm , H. J. Newberg , C. M. Rockosi , B. Yanny , Y. S. Lee

We report the spectroscopic analysis of 20 halo ab-type RR Lyrae stars with heliocentric distances between 15 and 165 kpc, conducted using medium-resolution spectra from the Magellan Inamori Kyocera Echelle (MIKE) spectrograph. We obtain…

We estimate the 3D density profile of the Galactic dark matter (DM) halo within $r \lesssim 30$ kpc from the Galactic centre by using the astrometric data for halo RR Lyrae stars from Gaia DR2. We model both the stellar halo distribution…

Astrophysics of Galaxies · Physics 2021-10-20 Kohei Hattori , Monica Valluri , Eugene Vasiliev

The shape and orientation of the Milky Way's dark matter halo remain poorly constrained. Observations of the accreted stellar halo show that it is triaxial and tilted with respect to the disc. If this configuration is long-lived, it can…

Astrophysics of Galaxies · Physics 2026-02-18 Adam M. Dillamore , Jason L. Sanders

We use the Stripe 82 proper motion catalogue of Bramich et al. (2008) to study the kinematics of Galactic disk stars in the solar neighborhood. We select samples of dwarf stars with reliable spectra and proper motions. They have cylindrical…

Astrophysics of Galaxies · Physics 2012-02-08 Martin C. Smith , S. Hannah Whiteoak , N. W. Evans

Using SDSS Stripe82 data we have obtained deep radial surface brightness profiles of 7 face-on to intermediate inclined late-type spirals down to \sim 30 mag arcsec^-2 in the r'-band. We do not find any evidence for a sharp cut-off of the…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-16 Judit Bakos , Ignacio Trujillo

The timing argument provides a lower limit on the mass of the Milky Way. We find, using a sample of 32 stars at $R > 60$ kpc drawn from the H3 Spectroscopic Survey and mock catalogs created from published numerical simulations, that…