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Large numbers of low-to-medium resolution spectra of M-type dwarf stars from both the local Galactic disk and halo are available from various surveys. In order to fully exploit these data, we develop a template-fit method using a set of…

Solar and Stellar Astrophysics · Physics 2020-03-11 Neda Hejazi , Sebastien Lepine , Derek Homeier , R. Michael Rich , Michael M. Shara

We present a spectroscopic study of Leo V, a recently discovered satellite of the Milky Way (MW). From stellar spectra obtained with the MMT/Hectochelle spectrograph we identify seven likely members of Leo V. Five cluster near the Leo V…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-13 Matthew G. Walker , Vasily Belokurov , N. Wyn Evans , Michael J. Irwin , Mario Mateo , Edward W. Olszewski , Gerard Gilmore

Halo stars orbit within the potential of the Milky Way and hence their kinematics can be used to understand the underlying mass distribution. However, the inferred mass distribution depends sensitively upon assumptions made on the density…

Astrophysics of Galaxies · Physics 2015-06-22 Prajwal R. Kafle , Sanjib Sharma , Geraint F. Lewis , Joss Bland-Hawthorn

Gravitational potential fluctuations driven by bursty star formation can kinematically 'heat up' dark matter at the centres of dwarf galaxies. A key prediction of such models is that, at a fixed dark matter halo mass, dwarfs with a higher…

Astrophysics of Galaxies · Physics 2019-04-15 J. I. Read , M. G. Walker , P. Steger

We report the discovery of high velocity candidates among RR~Lyrae stars found in the Milky Way halo. We identified 9 RR~Lyrae stars with Galactocentric velocities exceeding the local escape velocity based on the assumed Galaxy potential.…

We investigate whether the subhalos of Lambda-CDM galaxy halos have potentials consistent with the observed properties of Milky Way satellites, particularly those with high-quality photometric and kinematic data: Fornax, Leo I, Sculptor,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Louis E. Strigari , Carlos S. Frenk , Simon D. M. White

We present a kinematical study of the outer halo (r_GC approximately 60 to 160 kpc) of the Milky Way based on spectroscopy of 55 RR Lyrae stars obtained with the ESI instrument on the Keck II telescope. Our spectroscopic targets were…

We present a spectroscopic survey of the newly-discovered Canes Venatici dwarf galaxy using the Keck/DEIMOS spectrograph. Two stellar populations of distinct kinematics are found to be present in this galaxy: an extended, metal-poor…

Astrophysics · Physics 2009-11-11 Rodrigo Ibata , Scott Chapman , Mike Irwin , Geraint Lewis , Nicolas Martin

I provide a model rotation curve for the Milky Way that matches the details of the terminal velocity curve normalized to the Galactocentric distance $R_0 = 8.122$ kpc obtained by the GRAVITY collaboration and the corresponding circular…

Astrophysics of Galaxies · Physics 2018-08-29 Stacy McGaugh

The Hypervelocity Star survey presents the currently largest sample of radial velocity measurements of halo stars out to 80 kpc. We apply spherical Jeans modeling to these data in order to derive the mass profile of the Galaxy. We restrict…

Astrophysics of Galaxies · Physics 2010-08-31 Oleg Y. Gnedin , Warren R. Brown , Margaret J. Geller , Scott J. Kenyon

Nearly 400 Tycho-2 stars have been observed in a 720 square degree field in the direction of the North Galactic Pole with the high resolution echelle spectrograph ELODIE. Absolute magnitudes, effective temperatures, gravities and…

Astrophysics · Physics 2009-11-07 C. Soubiran , O. Bienaymé , A. Siebert

We have created a framework to facilitate the construction of specialized target lists for radial velocity surveys that are biased toward stars that (1) possess planets and (2) are easiest to observe with current detection techniques. We…

We use numerical simulations to examine the substructure within galactic and cluster mass halos that form within a hierarchical universe. Clusters are easily reproduced with a steep mass spectrum of thousands of substructure clumps that…

We have measured Keck/HIRES radial velocities for 30 candidate red giants in the direction of Palomar 13: an object traditionally cataloged as a compact, low-luminosity globular cluster. From a sample of 21 confirmed members, we find a…

Astrophysics · Physics 2009-11-07 Patrick Cote , S. G. Djorgovski , Georges Meylan , S. Castro , J. K. McCarthy

The dark matter halo surface density, given by the product of the dark matter core radius ($r_c$) and core density ($\rho_c$) has been shown to be a constant for a wide range of isolated galaxy systems. Here, we carry out a test of this…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-01 Gopika K , Shantanu Desai

We analyze the Illustris-1 hydrodynamical cosmological simulation to explore the stellar velocity dispersion of quiescent galaxies as an observational probe of dark matter halo velocity dispersion and mass. Stellar velocity dispersion is…

Astrophysics of Galaxies · Physics 2018-06-13 H. Jabran Zahid , Jubee Sohn , Margaret J. Geller

In this study, we modify the semi-analytic model Galacticus in order to accurately reproduce the observed properties of dwarf galaxies in the Milky Way. We find that reproducing observational determinations of the halo occupation fraction…

Astrophysics of Galaxies · Physics 2024-03-20 Niusha Ahvazi , Andrew Benson , Laura V. Sales , Ethan O. Nadler , Sachi Weerasooriya , Xiaolong Du , Mia Sauda Bovill

We present a comprehensive search for the 3.5 keV line, using $\sim$51 Ms of archival Chandra observations peering through the Milky Way's Dark Matter Halo from across the entirety of the sky, gathered via the Chandra Source Catalog Release…

High Energy Astrophysical Phenomena · Physics 2021-01-06 Dominic Sicilian , Nico Cappelluti , Esra Bulbul , Francesca Civano , Massimo Moscetti , Christopher S. Reynolds

Haro 2 , a nearby dwarf starburst dwarf galaxy with strong Ly alpha emission, hosts a starburst that has created outflows and filaments. The clear evidence for galactic outflow makes it an ideal candidate for studying the effects of…

Astrophysics of Galaxies · Physics 2020-03-18 Sara C. Beck , Pei-Ying Hsieh , Jean Turner
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