scholarly journals Evidence for Light-weight Local Group Dwarf Spheroidal Galaxies

2004 ◽  
Vol 220 ◽  
pp. 365-366
Author(s):  
J. R. Kuhn ◽  
D. Kocevski
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Local Group ◽  
Light Weight ◽  
Natural Explanation ◽  
Dwarf Spheroidal Galaxies ◽  
Ursa Minor ◽  
Matter Component ◽  
Morphological State ◽  
Spheroidal Galaxies

A simple and natural explanation for the dynamics and morphology of the Local Group Dwarf Spheroidal galaxies, Draco (Dra) and Ursa Minor (UMi), is that they are weakly unbound stellar systems with no significant dark matter component. A gentle, but persistent, Milky Way (MW) tide has left them in their current kinematic and morphological state (the “parametric tidal excitation”). A new test of a dark matter dominated dS potential follows from a careful observation of the “clumpiness” of the dS stellar surface density.

scholarly journals Too big to fail in light of Gaia

2019 ◽  
Vol 490 (1) ◽  
pp. 231-242 ◽  
Author(s):  
Manoj Kaplinghat ◽  
Mauro Valli ◽  
Hai-Bo Yu
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Large Scatter ◽  
Too Big To Fail ◽  
Dwarf Spheroidal Galaxies ◽  
Ursa Minor ◽  
Spheroidal Galaxies

ABSTRACT We point out an anticorrelation between the central dark matter (DM) densities of the bright Milky Way dwarf spheroidal galaxies (dSphs) and their orbital pericenter distances inferred from Gaia data. The dSphs that have not come close to the Milky Way centre (like Fornax, Carina and Sextans) are less dense in DM than those that have come closer (like Draco and Ursa Minor). The same anticorrelation cannot be inferred for the ultrafaint dSphs due to large scatter, while a trend that dSphs with more extended stellar distributions tend to have lower DM densities emerges with ultrafaints. We discuss how these inferences constrain proposed solutions to the Milky Way’s too-big-to-fail problem and provide new clues to decipher the nature of DM.

scholarly journals The Effect of Tidal Stripping on Composite Stellar Populations in Dwarf Spheroidal Galaxies

2010 ◽  
Vol 2010 ◽  
pp. 1-14 ◽  
Author(s):  
Laura V. Sales ◽  
Amina Helmi ◽  
Giuseppina Battaglia
Keyword(s):  
Dark Matter ◽  
Mass Loss ◽  
Milky Way ◽  
Velocity Dispersion ◽  
Local Group ◽  
Stellar Populations ◽  
Dwarf Spheroidal Galaxies ◽  
Stellar Component ◽  
Dwarf Spheroidals ◽  
Matter Component

We use N-body simulations to study the effects of tides on the kinematical structure of satellite galaxies orbiting a Milky Way-like potential. Here we focus on the evolution of a spherical, dark matter dominated satellite, which is modelled with two stellar components set ab initio to be spatially and kinematically segregated, in a way that resembles the configuration of the metal poor and metal rich stellar populations in several dwarf spheroidals of the Local Group. We find that an important attenuation of the initial differences in the distribution of the two stellar components occurs for orbits with small pericentric radii. This is mainly due to (i) the loss of the gravitational support provided by the dark matter component after tidal stripping takes place and (ii) tides preferentially affect the more extended stellar component, leading to a net decrease in its velocity dispersion as a response for the mass loss, which thus shrinks the kinematical gap. We apply these ideas to the Sculptor and Carina dwarf spheroidals. Differences in their orbits might help to explain why in the former a clear kinematical separation between metal poor and metal rich stars is apparent, while in Carina this segregation is significantly more subtle.

scholarly journals The Search for Dark Matter in Draco and Ursa Minor: A Three Year Progress Report

1987 ◽  
Vol 117 ◽  
pp. 153-160 ◽  
Author(s):  
M. Aaronson ◽  
E. Olszewski
Keyword(s):  
Dark Matter ◽  
Velocity Dispersion ◽  
Progress Report ◽  
Radial Velocities ◽  
Circumstantial Evidence ◽  
Dwarf Spheroidal Galaxies ◽  
Ursa Minor ◽  
Stellar Velocity ◽  
Atmospheric Motions ◽  
Matter Component

We report the cumulative results of an on-going effort to measure the stellar velocity dispersion in two nearby dwarf spheroidal galaxies. Radial velocities having an accuracy ≲ 2 km s−1 have now been secured for ten stars in Ursa Minor and eleven stars in Draco (including 16 K giants and 5 C types). Most objects have been observed at two or more epochs. Stars having non-variable velocities yield in both dwarfs a large (∼ 10 km s−1) dispersion. These results cannot be explained by atmospheric motions, and circumstantial evidence suggests that the effects of undetected binaries are also not likely to be important. Instead, it seems that both spheroidals contain a substantial dark matter component, which therefore must be “cold” in form.

scholarly journals Implication of Dark Matter Content in Dwarf Spheroidal Galaxies

1999 ◽  
Vol 192 ◽  
pp. 402-408
Author(s):  
H. Hirashita ◽  
T. T. Takeuchi ◽  
H. Kamaya
Keyword(s):  
Dark Matter ◽  
Local Group ◽  
Matter Content ◽  
Dwarf Spheroidal Galaxies ◽  
Large Velocity ◽  
The Galaxy ◽  
Correlation Tests ◽  
Tidal Heating ◽  
Physical Quantities ◽  
Spheroidal Galaxies

We investigate the dark matter (DM) content in the Local Group dwarf spheroidal galaxies (dSphs) by examining the correlations among their physical quantities. Two origins of the large velocity dispersions of the dSphs are possible: [1] the existence of DM and [2] tidal heating by the Galaxy. The correlation tests support both [1] and [2]. We finally mention circumstantial evidence for the existence of DM in the dSphs.

scholarly journals OBSERVATIONS OF MILKY WAY DWARF SPHEROIDAL GALAXIES WITH THEFERMI-LARGE AREA TELESCOPE DETECTOR AND CONSTRAINTS ON DARK MATTER MODELS

2010 ◽  
Vol 712 (1) ◽  
pp. 147-158 ◽  
Author(s):  
A. A. Abdo ◽  
M. Ackermann ◽  
M. Ajello ◽  
W. B. Atwood ◽  
L. Baldini ◽  
...  
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Large Area ◽  
Dwarf Spheroidal Galaxies ◽  
Spheroidal Galaxies

Stellar chemo-kinematics of isolated dwarf spheroidal galaxies

2018 ◽  
Vol 14 (S344) ◽  
pp. 222-223
Author(s):  
S. Taibi ◽  
G. Battaglia ◽  
M. Rejkuba ◽  
N. Kacharov ◽  
M. Zoccali
Keyword(s):  
Galaxy Evolution ◽  
Milky Way ◽  
Local Group ◽  
Intrinsic Properties ◽  
Dwarf Spheroidal Galaxies ◽  
Preliminary Results ◽  
Low Mass ◽  
Insight Into ◽  
Spheroidal Galaxies

AbstractThe study of dwarf spheroidal galaxies (dSph) is of great importance to understand galaxy evolution at the low-mass end. In the Local Group the majority of them are found to be satellites of the Milky Way or M31. The closest ones have been studied in great detail, however it is hard to constrain if their present-day observed properties are mainly caused by internal or environmental mechanisms. In order to minimize these effects and gain an insight into their intrinsic properties, we are studying two of the three isolated dSph galaxies in the Local Group, i.e. Cetus and Tucana, located far beyond the virial radius of the Milky Way and M31. We present here results from our recently published analysis of Cetus (Taibi2018) and preliminary results for Tucana (Taibi et al. in prep.).

scholarly journals Orbital Evidences for Dark-matter-free Milky Way Dwarf Spheroidal Galaxies

2020 ◽  
Vol 892 (1) ◽  
pp. 3 ◽  
Author(s):  
Francois Hammer ◽  
Yanbin Yang ◽  
Frederic Arenou ◽  
Jianling Wang ◽  
Hefan Li ◽  
...  
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Dwarf Spheroidal Galaxies ◽  
Spheroidal Galaxies

scholarly journals Observed Properties of Dark Matter on Small Spatial Scales

2007 ◽  
Vol 3 (S244) ◽  
pp. 44-52 ◽  
Author(s):  
Rosemary F.G. Wyse ◽  
Gerard Gilmore
Keyword(s):  
Dark Matter ◽  
Galaxy Evolution ◽  
Local Group ◽  
Spatial Scales ◽  
Critical Role ◽  
Large Datasets ◽  
Dwarf Spheroidal Galaxies ◽  
Internal Motions ◽  
Spheroidal Galaxies

AbstractThe nature of dark matter is one of the outstanding questions of astrophysics. The internal motions of member stars reveal that the lowest luminosity galaxies in the Local Group are the most dark-matter dominated. New large datasets allow one to go further, and determine systematic properties of their dark matter haloes. We summarise recent results, emphasising the critical role of the dwarf spheroidal galaxies in understanding both dark matter and baryonic processes that shape galaxy evolution.

The role of internal feedback in the evolution of the dwarf spheroidal galaxy Leo II

2019 ◽  
Vol 15 (S359) ◽  
pp. 278-279
Author(s):  
Roberto Hazenfratz ◽  
Gustavo A. Lanfranchi ◽  
Anderson Caproni
Keyword(s):  
Large Distance ◽  
Milky Way ◽  
Local Group ◽  
Galactic Evolution ◽  
External Effects ◽  
Dwarf Spheroidal Galaxies ◽  
First Results ◽  
Formation And Evolution ◽  
Spheroidal Galaxies

AbstractThis work aims to explore the different processes of formation and evolution of dwarf spheroidal galaxies in the Local Group analyzing internal and external feedbacks, taking Leo II as a model of parametrization due to its adequate large distance to the Milky Way, in order to minimize potential external effects. We present a discussion of the first results regarding the processes of formation and galactic evolution from the gas hydrodynamics. Combined with previous studies for other similar systems, such results have the potential to establish strong links for the elaboration of a consistent and coherent scenario of formation and evolution of the dwarf spheroidal galaxies in the Local Group.

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