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Based on the second Gaia data release (DR2), combined with the LAMOST and APOGEE spectroscopic surveys, we study the kinematics and metallicity distribution of the high-velocity stars that have a relative speed of at least 220 ${\rm km\…

Astrophysics of Galaxies · Physics 2020-11-18 Yepeng Yan , Cuihua Du , Hefan Li , Jianrong Shi , Jun Ma , Heidi Jo Newberg

We apply a Bayesian method to model multi-epoch radial velocity measurements in the ultra-faint dwarf galaxy Reticulum II, fully accounting for the effects of binary orbital motion and systematic offsets between different spectroscopic…

Astrophysics of Galaxies · Physics 2019-06-12 Quinn E. Minor , Andrew B. Pace , Jennifer L. Marshall , Louis E. Strigari

We present line-of-sight stellar velocity distributions of elliptical galaxy NGC 821 obtained to approximately 100 arcsec (over 2 effective radii) with long-slit spectroscopy from the Hobby-Eberly Telescope. Our measured stellar…

Astrophysics · Physics 2011-01-20 Amy Forestell , Karl Gebhardt

The dwarf satellite galaxies of the Milky Way Crater II and Antlia II have uncommonly low dynamical mass densities, due to their large size and low velocity dispersion. Previous work have failed to identify formation scenarios within the…

Astrophysics of Galaxies · Physics 2019-08-14 Nicola C. Amorisco

Recently, \cite{vanDokkum2018} have presented an important discovery of an ultra diffuse galaxy, NGC1052-DF2, with a dark matter content significantly less than predicted from its stellar mass alone. The analysis relies on measured radial…

Astrophysics of Galaxies · Physics 2019-01-03 Adi Nusser

We investigate the evolution in the dark matter halo circular velocity function, measured at a fixed physical radius of 20 kpc (v_20), which is likely to be a good proxy for galaxy circular velocity, in the Millennium-II simulation. We find…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Simone M. Weinmann , Marijn Franx , Pieter van Dokkum , Rachel Bezanson

We report new constraints on the local escape speed of our Galaxy. Our analysis is based on a sample of high velocity stars from the RAVE survey and two previously published datasets. We use cosmological simulations of disk galaxy formation…

We present stellar velocity dispersion profiles for seven Milky Way dwarf spheroidal (dSph) satellite galaxies. We have measured 8394 line-of-sight velocities (+/- 2.5 km/s) for 6804 stars from high-resolution spectra obtained at the…

We present a catalog of 5,290 RR Lyrae stars (RRLs) with metallicities estimated from spectra of the LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) and the Sloan Extension for Galactic Understanding and Exploration…

Solar and Stellar Astrophysics · Physics 2020-04-15 G. -C. Liu , Y. Huang , H. -W. Zhang , M. -S. Xiang , J. -J. , Ren , B. -Q. Chen , H. -B. Yuan , C. Wang , Y. Yang , Z. -J. Tian , F. Wang , X. -W. Liu

Well determined radial velocities and abundances are essential for analyzing the properties of the Globular Cluster system of the Milky Way. However more than 50% of these clusters have no spectroscopic measure of their metallicity. In this…

An accurate knowledge of the dark matter distribution in the Milky Way is of crucial importance for galaxy formation studies and current searches for particle dark matter. In this paper we set new dynamical constraints on the Galactic dark…

Astrophysics of Galaxies · Physics 2015-12-03 Miguel Pato , Fabio Iocco , Gianfranco Bertone

Rates for detection of weakly-interacting massive-particle (WIMP) dark matter are usually carried out assuming the Milky Way halo is an isothermal sphere. However, it is possible that our halo is not precisely spherical; it may have some…

High Energy Physics - Phenomenology · Physics 2010-11-30 Marc Kamionkowski , Ali Kinkhabwala

We review the various techniques used to constrain the Galactic halo mass profile for radii > 20 kpc with particular emphasis on identifying a self-consistent halo model and resolving the apparent discrepancies present in the literature on…

Astrophysics · Physics 2007-05-23 Dennis Zaritsky

In this paper, we construct the circular velocity curve of the Milky Way out to $\sim 30$ kpc, providing an updated model of the dark matter density profile. We derive precise parallaxes for 120,309 stars with a data-driven model, using…

Astrophysics of Galaxies · Physics 2023-05-30 Xiaowei Ou , Anna-Christina Eilers , Lina Necib , Anna Frebel

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

We present first results from a Keck/DEIMOS spectroscopic survey of red giant branch (RGB) stars in M33. The radial velocity distributions of the stars in our fields are well described by three Gaussian components, corresponding to a…

We present a search and analysis of variable stars in the recently discovered Crater~II dwarf galaxy. Based on $B$, $V$, $I$ data collected with the Isaac Newton Telescope (FoV$\sim$0.44 square degrees) we detected 37 variable stars, of…

We announce the discovery of a new Milky Way satellite Segue 2 found in the data of the Sloan Extension for Galactic Understanding and Exploration (SEGUE). We followed this up with deeper imaging and spectroscopy on the Multiple Mirror…

Astrophysics of Galaxies · Physics 2010-03-01 V. Belokurov , M. G. Walker , N. W. Evans , G. Gilmore , M. J. Irwin , M. Mateo , L. Mayer , E. Olszewski , J. Bechtold , T. Pickering

We measure the central kinematics for the dwarf spheroidal galaxy Leo I using integrated-light measurements and previously published data. We find a steady rise in the velocity dispersion from $300^{\prime\prime}$ into the center. The…

It has been recently claimed that the confined structure of the debris from the Sagittarius dwarf implies that the dark-matter halo of our Galaxy should be nearly spherical, in strong contrast with predictions from cold dark-matter (CDM)…

Astrophysics · Physics 2009-11-10 Amina Helmi