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We discuss the first part of a survey for RR Lyrae variables in the galactic halo that is being made with the 1m Schmidt telescope at the Venezuelan National Observatory. So far the survey has discovered 497 variables in 380 sq. degrees,…

Astrophysics · Physics 2007-05-23 A. Katherina Vivas , Robert Zinn

The kinematics of the stellar halo hold important clues to the assembly history and mass distribution of the Galaxy. In this study, we map the kinematics of stars across the Galactic halo with the H3 Survey. We find a complex distribution…

Astrophysics of Galaxies · Physics 2024-06-21 Jiwon Jesse Han , Charlie Conroy , Dennis Zaritsky , Ana Bonaca , Nelson Caldwell , Vedant Chandra , Yuan-Sen Ting

Kinematic studies have produced accurate measurements of the total dark matter mass and mean dark matter density within the optical extent of galaxies, for large samples of objects. Here we consider theoretical predictions for the latter…

Astrophysics of Galaxies · Physics 2019-07-10 James E. Taylor , Jihye Shin , Nathalie N. -Q. Ouellette , Stéphane Courteau

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 model the mass distributions of 40 high surface brightness spiral galaxies inside their optical radii, deriving parameters of mass models by matching the predicted velocities to observed velocity maps. We use constant mass-to-light disk…

Astrophysics · Physics 2009-11-10 Eric I. Barnes , J. A. Sellwood , Arthur Kosowsky

We improve the identification and isolation of individual stellar populations in the Galactic halo based on an updated set of empirically calibrated stellar isochrones in the Sloan Digital Sky Survey (SDSS) and Pan-STARRS 1 (PS1)…

Astrophysics of Galaxies · Physics 2021-02-10 Deokkeun An , Timothy C. Beers

High-velocity stars in the Galactic halo, e.g. the so-called hyper-velocity stars (HVS), are important tracers of the properties of the dark matter halo, in particular its mass. Based on the SDSS DR6 spectral database a search for the…

Solar and Stellar Astrophysics · Physics 2015-05-20 A. Tillich , U. Heber , S. Geier , H. Hirsch , P. F. L. Maxted , B. T. Gänsicke , T. R. Marsh , R. Napiwotzki , R. H. Østensen , R. -D. Scholz

We study the density profile and shape of the Galactic halo using deep multicolour images from the MENeaCS and CCCP projects, over 33 fields selected to avoid overlap with the Galactic plane. Using multicolour selection and PSF…

Astrophysics of Galaxies · Physics 2015-06-24 B. Pila-Díez , J. T. A. de Jong , K. Kuijken , R. F. J. van der Burg , H. Hoekstra

We develop statistical methods for identifying star streams in the halo of the Milky Way galaxy that exploit observed spatial and radial velocity distributions. Within a great circle, departures of the observed spatial distribution from…

Astrophysics of Galaxies · Physics 2015-06-03 Charles King , Warren R. Brown , Margaret J. Geller , Scott J. Kenyon

We run numerical simulations of the disruption of satellite galaxies in a Galactic potential to build up the entire stellar halo, in order to investigate what the next generation of astrometric satellites will reveal by observing the halo…

Astrophysics · Physics 2009-10-31 Amina Helmi , P. Tim de Zeeuw

Numerical simulations of dwarf spheroidal galaxies undergoing several close encounters with the Milky Way are described. By comparing our models to observed properties of the recently discovered dwarf galaxy in Sagittarius (Sgr), we discuss…

Astrophysics · Physics 2016-08-30 Kathryn V. Johnston , David N. Spergel , Lars Hernquist

We use the SDSS-Gaia catalogue to search for substructure in the stellar halo. The sample comprises 62\,133 halo stars with full phase space coordinates and extends out to heliocentric distances of $\sim 10$ kpc. As actions are conserved…

Astrophysics of Galaxies · Physics 2018-07-03 G. C. Myeong , N. W. Evans , V. Belokurov , J. L. Sanders , S. E. Koposov

The structure and kinematics of the recognized stellar components of the Milky Way are explored, based on well-determined atmospheric parameters and kinematic quantities for 32360 calibration stars from the Sloan Digital Sky Survey (SDSS)…

Tidal debris from infalling satellites can leave observable structure in the phase-space distribution of the Galactic halo. Such substructure can be manifest in the spatial and/or velocity distributions of the stars in the halo. This paper…

Astrophysics of Galaxies · Physics 2015-06-15 Mariangela Lisanti , David N. Spergel , Piero Madau

We measure the angular 2-point correlation functions of galaxies in a volume limited, photometrically selected galaxy sample from the fifth data release of the Sloan Digital Sky Survey. We split the sample both by luminosity and galaxy type…

Cosmology and Nongalactic Astrophysics · Physics 2011-04-20 Ashley J Ross , Robert J. Brunner

Sloan Digital Sky Survey (SDSS) DR5 photometric data with $120^{\circ} < \alpha < 270^{\circ}$, $25^{\circ} < \delta < 70^{\circ}$ are searched for new Milky Way companions or substructures in the Galactic halo. Five candidates are…

Astrophysics · Physics 2011-11-09 C. Liu , J. Hu , H. Newberg , Y. Zhao

Recent studies show that the Milky Way stellar halo is composed of populations of different origins, shaped by multiple accretion events. To better understand the formation of the Milky Way and other spiral galaxies, we characterize the…

We use the astrometric and photometric data from Gaia Data Release 2 and line-of-sight velocities from various other surveys to study the 3d structure and kinematics of the Sagittarius dwarf galaxy. The combination of photometric and…

Astrophysics of Galaxies · Physics 2020-09-24 Eugene Vasiliev , Vasily Belokurov

The observed flaring of HI disk in the outer region of galaxies has been used in the past to determine the shape of the dark matter halo. Previous studies based on this concept suggest a slightly oblate halo (axis ratio ~ 0.8) for our…

Astrophysics · Physics 2009-11-11 C. A. Narayan , K. Saha , C. J. Jog

The inner Galactic halo is a complex graveyard of the Milky Way's earliest accretion events, where severe orbital phase-mixing challenges traditional dynamical stream-finding techniques. We present a purely data-driven, 12-dimensional…

Astrophysics of Galaxies · Physics 2026-05-25 Furkan Akbaba , Olcay Plevne