scholarly journals Torsion Gravity

2021 ◽  
Vol 2 (12) ◽  
pp. 1309-1314
Author(s):  
Konstantinov SI
Keyword(s):  
Dark Matter ◽  
Space Time ◽  
Space Environment ◽  
Theoretical Physics ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Quantum Vacuum ◽  
Spatial Curvature ◽  
Continuous Space

Based on the discovery by astrophysicists of dark matter halos around galaxies, stars and planets, it became possible to abandon the speculative concept of the spatial curvature of Einstein's space-time fabric and geometric gravity. Torsional gravity and spinors in fundamental theoretical physics should be based on a new cosmology, including a dark matter halo rotating with planets, stars and galaxies and forming funnels in the continuous space environment of a quantum vacuum (dark matter). The article discusses the nature of tornado and tropical hurricanes.

scholarly journals THE ASYMPTOTIC STRUCTURE OF SPACE-TIME

2003 ◽  
Vol 12 (09) ◽  
pp. 1743-1750 ◽  
Author(s):  
FRED C. ADAMS ◽  
MICHAEL T. BUSHA ◽  
AUGUST E. EVRARD ◽  
RISA H. WECHSLER
Keyword(s):  
Dark Matter ◽  
Vacuum Energy ◽  
Space Time ◽  
Dark Matter Halo ◽  
Constant Density ◽  
Dark Matter Halos ◽  
Asymptotic Structure ◽  
Density Profiles ◽  
Near Future ◽  
Universal Geometry

Astronomical observations strongly suggest that our universe is now accelerating and contains a substantial admixture of dark vacuum energy. Using numerical simulations to study this newly consolidated cosmological model (with a constant density of dark energy), we show that astronomical structures freeze out in the near future and that the density profiles of dark matter halos approach the same general form. Every dark matter halo grows asymptotically isolated and thereby becomes the center of its own island universe. Each of these isolated regions of space-time approaches a universal geometry and we calculate the corresponding form of the space-time metric.

scholarly journals Recoiling black holes in static and evolving dark matter halo potential

2015 ◽  
pp. 17-28 ◽  
Author(s):  
M. Smole
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Critical Velocity ◽  
Complete Removal ◽  
Matter Density ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Critical Amplitude ◽  
Density Distributions

We follow trajectories of kicked black holes in static and evolving dark matter halo potential. We explore both NFW and Einasto dark matter density distributions. Considered dark matter halos represent hosts of massive spiral and elliptical field galaxies. We study critical amplitude of kick velocity necessary for complete black hole ejection at various redshifts and find that ~40% lower kick velocities can remove black holes from their host haloes at z = 7 compared to z = 1. The greatest difference between static and evolving potential occurs near the critical velocity for black hole ejection and at high redshifts. When NFW and Einasto density distributions are compared ~30% higher kick velocities are needed for complete removal of BHs from dark matter halo described by NFW profile.

scholarly journals Structure of Dark Matter Halo

1999 ◽  
Vol 183 ◽  
pp. 155-155
Author(s):  
Toshiyuki Fukushige ◽  
Junichiro Makino
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Temperature Inversion ◽  
Dark Matter Halo ◽  
Temperature Structure ◽  
Galactic Halos ◽  
Dark Matter Halos ◽  
Density Profiles ◽  
Order Of Magnitude ◽  
Special Purpose Computer

We performed N-body simulation on special-purpose computer, GRAPE-4, to investigate the structure of dark matter halos (Fukushige, T. and Makino, J. 1997, ApJL, 477, L9). Universal profile proposed by Navarro, Frenk, and White (1996, ApJ, 462, 563), which has cusp with density profiles ρ ∝r−1in density profile, cannot be reproduced in the standard Cold Dark Matter (CDM) picture of hierarchical clustering. Previous claims to the contrary were based on simulations with relatively few particles, and substantial softening. We performed simulations with particle numbers an order of magnitude higher, and essentially no softening, and found that typical central density profiles are clearly steeper than ρ ∝r−1, as shown in Figure 1. In addition, we confirm the presence of a temperature inversion in the inner 5 kpc of massive galactic halos, and give a natural explanation for formation of the temperature structure.

scholarly journals The dark matter halos of spheroidal galaxies and clusters of galaxies

2004 ◽  
Vol 220 ◽  
pp. 159-164 ◽  
Author(s):  
Tommaso Treu ◽  
Léon V. E. Koopmans ◽  
David J. Sand ◽  
Graham P. Smith ◽  
Richard S. Ellis
Keyword(s):  
Dark Matter ◽  
Mass Density ◽  
Hubble Constant ◽  
Dark Matter Halo ◽  
Dynamical Analysis ◽  
Delay Systems ◽  
Clusters Of Galaxies ◽  
Dark Matter Halos ◽  
Gravitational Lenses ◽  
Stellar Component

We describe the first results from two observational projects aimed at measuring the amount and spatial distribution of dark matter in distant early-type galaxies (E/S0s) and clusters of galaxies. At the galaxy scale, the Lenses Structure and Dynamics (LSD) Survey is gathering kinematic data for distant (up to z ⋐ 1) E/S0s that are gravitational lenses. A joint lensing and dynamical analysis constrains the fraction of dark matter within the Einstein radius, the mass-to-light ratio of the stellar component, and the total slope of the mass density profile. These properties and their evolution with redshift are briefly discussed in terms of the formation and evolution of E/S0 galaxies and measurement of the Hubble Constant from gravitational time delay systems. At the cluster scale – after careful removal of the stellar component with a joint lensing and dynamical analysis – systems with giant radial arcs can be used to measure precisely the inner slope of the dark matter halo. An HST search for radial arcs and the analysis of a first sample are briefly discussed in terms of the universal dark matter halos predicted by CDM simulations.

The Role of the Radial Orbit Instability in Dark Matter Halo Formation and Structure

2006 ◽  
Vol 2 (S235) ◽  
pp. 124-124
Author(s):  
J. M. Meyer ◽  
J. J. Dalcanton ◽  
T. R. Quinn ◽  
L. L. R. Williams ◽  
E. I. Barnes ◽  
...  
Keyword(s):  
Dark Matter ◽  
Density Profile ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Radial Orbit ◽  
Profile Changes ◽  
Analytic Models ◽  
The Universe ◽  
Scale Length

AbstractFor nearly a decade, N-body simulations have revealed a nearly universal dark matter density profile. This density profile appears to be robust to changes in the overall density of the universe and the underlying power spectrum. Despite its universality, however, the physical origin of this profile has not yet been well understood. Semi-analytic models have suggested that scale lengths in dark matter halos may be determined by the onset of the radial orbit instability. We have tested this theory using N-body simulations of collapsing dark matter halos. The resulting halo structures are prolate in shape, due to the mild aspect of the instability. We find that the radial orbit instability sets a scale length at which the velocity dispersion changes rapidly from isotropic to radially anisotropic. Preliminary analysis suggests that this scale length is proportional to the radius at which the density profile changes shape, as is the case in the semi-analytic models; however, the coefficient of proportionality is different by a factor of ~2. We conclude that the radial orbit instability may be a key physical mechanism responsible for the nearly universal profiles of simulated dark matter halos.

The Nexus graviton: A quantum of Dark Energy and Dark Matter

2014 ◽  
Vol 11 (06) ◽  
pp. 1450059 ◽  
Author(s):  
Stuart Marongwe
Keyword(s):  
Dark Matter ◽  
Quantum Theory ◽  
Dark Energy ◽  
Space Time ◽  
Current Paper ◽  
Quantum Vacuum ◽  
Self Consistent ◽  
Published Paper

In a recently published paper called Nexus: A quantum theory of space-time, gravity and the quantum vacuum by the above author, a plausible self-consistent quantum theory of space-time, gravity and the quantum vacuum is provided. In this current paper the author focuses primarily on the graviton as described in Nexus as a solution to the enigmatic phenomena of Dark Energy and Dark Matter as well as includes corrections to the first paper.

Rotation Curve and Dark Matter Halo profile in Finsler Geometry

2020 ◽  
Author(s):  
Nupur Paul ◽  
Farook Rahaman ◽  
Nasarul Islam ◽  
S.S. De
Keyword(s):  
Dark Matter ◽  
Rotational Velocity ◽  
Finsler Geometry ◽  
Outer Region ◽  
Recent Time ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Radial Profiles ◽  
Galactic Dark Matter ◽  
Specific Equation

Galactic dark matter is an active area of research in recent time. Several researchers proposed several descriptions of radial profiles of dark matter halos by using N-body simulations. Among them, Navarro, Frenk and White (NFW) dark matter profile provides the most accurate description of dark matter halos. It is believed that dark matter is smooth and distributed uniformly throughout space. Using Finslerian geometrical background and a specific equation of state, we propose a new way to estimate the rotational velocity of galaxies based on the NFW dark matter profile. On small scales the first few distances (about 30 kpc) the velocity increases whereas in the outer region of the galaxies, the rotational velocity is found to be more or less constant which supports observed rotational velocities.

scholarly journals Tidal Tails and the Shape of the Dark Matter Halo

2005 ◽  
Vol 22 (3) ◽  
pp. 190-194 ◽  
Author(s):  
Geraint F. Lewis ◽  
Rodrigo A. Ibata
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Dwarf Galaxy ◽  
Observational Evidence ◽  
Dark Matter Halo ◽  
Dark Matter Halos ◽  
Fundamental Understanding ◽  
Tidal Tails ◽  
Precise Interpretation

AbstractCold dark matter cosmologies successfully accounts for the distribution of matter on large scales. On smaller scales, these cosmological models predict that galaxies like our own Milky Way should be enveloped in massive dark matter halos. Furthermore, these halos should be significantly flattened or even triaxial. Recent observational evidence, drawn from the demise of the Sagittarius dwarf galaxy as it is cannibalized by our own, indicates that the potential of the Milky Way must be close to spherical. While the precise interpretation of the observational evidence is under debate, an apparently spherical halo may signify a pronounced failing of dark matter models, and may even indicate a failure in our fundamental understanding of gravity.

scholarly journals DISTRIBUTION FUNCTION IN THE CENTER OF THE DARK MATTER HALO

2009 ◽  
Vol 18 (03) ◽  
pp. 477-484
Author(s):  
DING MA ◽  
PING HE
Keyword(s):  
Dark Matter ◽  
Distribution Function ◽  
Phase Space ◽  
Velocity Dispersion ◽  
Anisotropy Parameter ◽  
Dark Matter Halo ◽  
Phase Space Density ◽  
Dark Matter Halos ◽  
Density Profiles ◽  
Space Density

N-body simulations of dark matter halos show that the density profiles of the halos behave as ρ(r) ∝ r-α(r), where the density logarithmic slope α ≃ 1–1.5 in the center and α ≃ 3–4 in the outer parts of the halos. However, some observations are not in agreement with simulations in the very central region of the halos. The simulations also show that the velocity dispersion anisotropy parameter β ≈ 0 in the inner part of the halo and the so-called pseudo–phase-space density ρ/σ3 behaves as a power law in radius r. With these results in mind, we study the distribution function and the pseudo–phase-space density ρ/σ3 of the center of dark matter halos and find that they are closely related.

scholarly journals Numerical Simulation of the Dwarf Companions of Giant Galaxies

2007 ◽  
Vol 3 (S244) ◽  
pp. 226-230
Author(s):  
A. H. Nelson ◽  
P. R. Williams
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Initial Conditions ◽  
Dark Matter Halo ◽  
Initial Population ◽  
Dark Matter Halos ◽  
Disc Galaxy ◽  
Standard Spectrum ◽  
The Galaxy ◽  
Secondary Population

AbstractWe report simulations of the formation of a giant disc galaxy from cosmological initial conditions. Two sets of initial conditions are used, initially smooth density for both gas and stars, representing the Warm dark Matter scenario, and an initially fluctuating density representing the standard spectrum for the Cold dark Matter scenario. For the WDM initial conditions, the galaxy has a population of long lived dwarf satellites at z = 0, with orbits close to a plane coincident with that of the giant galaxy disc. The detailed properties of these dwarfs mimic closely the observed properties of Local Group dwarfs with respect to mass, and kinematics. However they do not have individual dark matter halos, but orbit in the nearly spherical dark matter halo of the giant galaxy. The reason for this is that the initial population of dwarf dark matter haloes, which form during the initial collapse phase, all merge into the halo of the giant galaxy within a few to several Gyears, while the long lived dwarfs form as a secondary population by gravitational collapse of high angular momentum gas in the outer reaches of the giants proto-galactic disc. Due to their late formation and their more distant orbits, they survive until the present epoch as individual dwarf galaxies at radii 20-50kpc from the giants centre. For CDM initial conditions there are many more dwarf satellites at z = 0, some of which form early on as gas condensations in DM sub-halos, and survive with these individual DM halos till z = 0 due to their being sufficiently well bound to avoid merging with the main galaxy. However even in this case some second generation satellites form as initially gas only objects, just as for the smooth initial conditions of WDM.

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