scholarly journals Dark matter distribution and dynamics of dwarf spheroidal galaxies

2019 ◽  
Vol 14 (S353) ◽  
pp. 239-245
Author(s):  
Ewa L. Łokas
Keyword(s):  
Dark Matter ◽  
Velocity Dispersion ◽  
Matter Content ◽  
Current Status ◽  
Superposition Method ◽  
Matter Distribution ◽  
Dwarf Spheroidal Galaxies ◽  
Dark Matter Distribution ◽  
Dynamical Modelling ◽  
Spheroidal Galaxies

AbstractI review the current status of dynamical modelling of dwarf spheroidal galaxies focusing on estimates of their dark matter content. Starting with the simplest methods using the velocity dispersion profiles I discuss the inherent issues of mass-anisotropy degeneracy and contamination by unbound stars. I then move on to methods of increasing complexity, aiming to break the degeneracy, up to recent applications of the Schwarzschild orbit superposition method. The dynamical modelling is placed in the context of possible scenarios for the formation of dwarf spheroidal galaxies, including the tidal stirring model and mergers of dwarf galaxies. The two scenarios are illustrated with examples from simulations: a comparison between the tidal evolution of dwarfs with cuspy and cored dark matter profiles and the formation of a dwarf spheroidal with prolate rotation.

scholarly journals Dark matter distribution in the Galactic dwarf spheroidal galaxies

2020 ◽  
Vol 1468 ◽  
pp. 012011
Author(s):  
Kohei Hayashi ◽  
Shigeki Matsumoto ◽  
Masahiro Ibe ◽  
Mino N. Ishigaki ◽  
Hajime Sugai ◽  
...  
Keyword(s):  
Dark Matter ◽  
Matter Distribution ◽  
Dwarf Spheroidal Galaxies ◽  
Dark Matter Distribution ◽  
Spheroidal Galaxies

scholarly journals Imprint of Pressure on Characteristic Dark Matter Profiles: The Case of ESO0140040

Galaxies ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 74
Author(s):  
Kuantay Boshkayev ◽  
Talgar Konysbayev ◽  
Ergali Kurmanov ◽  
Orlando Luongo ◽  
Marco Muccino
Keyword(s):  
Dark Matter ◽  
Complex Structure ◽  
Matter Content ◽  
Model Parameters ◽  
Matter Distribution ◽  
Density Profiles ◽  
The Galaxy ◽  
Dark Matter Distribution ◽  
Observational Signature

We investigate the dark matter distribution in the spiral galaxy ESO0140040, employing the most widely used density profiles: the pseudo-isothermal, exponential sphere, Burkert, Navarro-Frenk-White, Moore and Einasto profiles. We infer the model parameters and estimate the total dark matter content from the rotation curve data. For simplicity, we assume that dark matter distribution is spherically symmetric without accounting for the complex structure of the galaxy. Our predictions are compared with previous results and the fitted parameters are statistically confronted for each profile. We thus show that although one does not include the galaxy structure it is possible to account for the same dynamics assuming that dark matter provides a non-zero pressure in the Newtonian approximation. In this respect, we solve the hydrostatic equilibrium equation and construct the dark matter pressure as a function for each profile. Consequently, we discuss the dark matter equation of state and calculate the speed of sound in dark matter. Furthermore, we interpret our results in view of our approach and we discuss the role of the refractive index as an observational signature to discriminate between our approach and the standard one.

scholarly journals Tidal forces from the wake of dynamical friction: warps, lopsidedness, and kinematic misalignment

2020 ◽  
Vol 498 (1) ◽  
pp. 1080-1092
Author(s):  
Rain Kipper ◽  
María Benito ◽  
Peeter Tenjes ◽  
Elmo Tempel ◽  
Roberto de Propris
Keyword(s):  
Dark Matter ◽  
Velocity Dispersion ◽  
Position Angle ◽  
Back Reaction ◽  
Dynamical Friction ◽  
Matter Distribution ◽  
Tidal Forces ◽  
Isolated Galaxies ◽  
The Galaxy ◽  
Dark Matter Distribution

ABSTRACT A galaxy moving through a background of dark matter particles induces an overdensity of these particles or a wake behind it. The back reaction of this wake on the galaxy is a force field that can be decomposed into an effective deceleration (called dynamical friction) and a tidal field. In this paper, we determine the tidal forces, thus generated on the galaxy, and the resulting observables, which are shown to be warps, lopsidedness, and/or kinematic-photometric position angle misalignments. We estimate the magnitude of the tidal-like effects needed to reproduce the observed warp and lopsidedness on the isolated galaxy IC 2487. Within a realistic range of dark matter distribution properties, the observed, warped, and lopsided kinematical properties of IC 2487 are possible to reproduce (the background medium of dark matter particles has a velocity dispersion of $\lesssim 80\, {\rm km\, s^{-1}}$ and the density $10^4{\!-\!}10^5\, {\rm M_\odot \, kpc^{-3}}$, more likely at the lower end). We conclude that the proposed mechanism can generate warps, lopsidedness, and misalignments observed in isolated galaxies or galaxies in loose groups. The method can be used also to constrain dark matter spatial and velocity distribution properties.

Effects of non-vanishing dark matter pressure in the Milky Way Galaxy

2021 ◽  
Vol 508 (1) ◽  
pp. 1543-1554
Author(s):  
K Boshkayev ◽  
T Konysbayev ◽  
E Kurmanov ◽  
O Luongo ◽  
D Malafarina ◽  
...  
Keyword(s):  
Black Hole ◽  
Dark Matter ◽  
Gravitational Lensing ◽  
Matter Content ◽  
Dark Matter Halo ◽  
Matter Distribution ◽  
Milky Way Galaxy ◽  
The Galaxy ◽  
Dark Matter Distribution ◽  
Inner Parts

ABSTRACT We consider the possibility that the Milky Way’s dark matter halo possesses a non-vanishing equation of state. Consequently, we evaluate the contribution due to the speed of sound, assuming that the dark matter content of the galaxy behaves like a fluid with pressure. In particular, we model the dark matter distribution via an exponential sphere profile in the galactic core, and inner parts of the galaxy whereas we compare the exponential sphere with three widely used profiles for the halo, i.e. the Einasto, Burkert and Isothermal profile. For the galactic core, we also compare the effects due to a dark matter distribution without black hole with the case of a supermassive black hole in vacuum and show that present observations are unable to distinguish them. Finally we investigate the expected experimental signature provided by gravitational lensing due to the presence of dark matter in the core.

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 Simulating Globular Clusters in Dark Matter Subhalos

2022 ◽  
Vol 924 (2) ◽  
pp. 77
Author(s):  
Raymond G. Carlberg ◽  
Laura C. Keating
Keyword(s):  
Dark Matter ◽  
Globular Clusters ◽  
Milky Way ◽  
Velocity Dispersion ◽  
Star Clusters ◽  
Stellar Mass ◽  
Matter Distribution ◽  
Circular Velocity ◽  
Central Value ◽  
Dark Matter Distribution

Abstract A cosmological zoom-in simulation that develops into a Milky Way-like halo begins at redshift 7. The initial dark matter distribution is seeded with dense star clusters of median mass 5 × 105 M ⊙, placed in the largest subhalos present, which have a median peak circular velocity of 25 km s−1. Three simulations are initialized using the same dark matter distribution with the star clusters starting on approximately circular orbits having initial median radii 6.8, 0.14 kpc, and, at the exact center of the subhalos. The simulations are evolved to the current epoch at which time the median galactic orbital radii of the three sets of clusters are 30, 5, and 16 kpc, with the clusters losing about 2%, 50%, and 15% of their mass, respectively. Clusters beginning at small orbital radii have so much tidal forcing that they are often not in equilibrium. Clusters that start at larger subhalo radii have a velocity dispersion that declines smoothly to ≃20% of the central value at ≃20 half-mass radii. The clusters that begin in the subhalo centers can show a rise in velocity dispersion beyond 3–5 half-mass radii. That is, the clusters that form without local dark matter always have stellar-mass-dominated kinematics at all radii, whereas about 25% of the clusters that begin in subhalo centers have remnant local dark matter.

scholarly journals Tracing the Dynamical Mass in Galaxy Disks Using H i Velocity Dispersion and Its Implications for the Dark Matter Distribution in Galaxies

2020 ◽  
Vol 889 (1) ◽  
pp. 10 ◽  
Author(s):  
Mousumi Das ◽  
Stacy S. McGaugh ◽  
Roger Ianjamasimanana ◽  
James Schombert ◽  
K. S. Dwarakanath
Keyword(s):  
Dark Matter ◽  
Velocity Dispersion ◽  
Matter Distribution ◽  
Dynamical Mass ◽  
Dark Matter Distribution

scholarly journals About the morphology of dwarf spheroidal galaxies and their dark matter content

2003 ◽  
Vol 406 (3) ◽  
pp. 847-854 ◽  
Author(s):  
C. J. Walcher ◽  
J. W. Fried ◽  
A. Burkert ◽  
R. S. Klessen
Keyword(s):  
Dark Matter ◽  
Matter Content ◽  
Dwarf Spheroidal Galaxies ◽  
Spheroidal Galaxies
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