scholarly journals Analysis of repulsive central universal force field on solar and galactic dynamics

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 364-372
Author(s):  
Kamal Barghout
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Force Field ◽  
Galactic Halo ◽  
Galactic Plane ◽  
Yukawa Potential ◽  
Galactic Rotation ◽  
Gravitational Theories ◽  
Universal Force Field ◽  
Modify Gravity

AbstractRecent astrophysical observations hint toward the need for an extended theory of gravity to explain puzzles presented by the standard cosmological model such as the need for dark matter and dark energy to understand the dynamics of the cosmos. This paper investigates the effect of a repulsive central universal force field on the behavior of celestial objects. Negative tidal effect on the solar and galactic orbits, like that experienced by Pioneer spacecrafts, was derived from the central force and was shown to manifest itself as dark matter and dark energy. Vertical oscillation of the sun about the galactic plane was modeled as simple harmonic motion driven by the repulsive force. The proposed universal field was used to infer the shape of dark matter halos as generated from a planar component of the universal force and to explain galactic warp, galactic halo density, and galactic rotation curves. It was found that the repulsive field addition to Newton’s gravity mimics the Yukawa potential correction employed by many current gravitational theories that modify gravity.

scholarly journals Possible formation of wormholes from dark matter in an isothermal galactic halo and void

2019 ◽  
Vol 34 (23) ◽  
pp. 1950188
Author(s):  
Nayan Sarkar ◽  
Susmita Sarkar ◽  
Farook Rahaman ◽  
P. K. F. Kuhfittig ◽  
G. S. Khadekar
Keyword(s):  
Dark Matter ◽  
Galactic Halo ◽  
Energy Condition ◽  
Null Energy Condition ◽  
Galactic Rotation ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Rotation Curves ◽  
Galactic Rotation Curves ◽  
Traversable Wormholes

It is well-known that traversable wormholes are valid solutions of the Einstein field equations, but these structures can only be maintained by violating the null energy condition. In this paper, we have obtained such wormhole solutions in an isothermal galactic halo, as well as in a void. We have shown that the null energy condition is violated, with the help of a suitable redshift function obtained from flat galactic rotation curves.

Relational Blockworld Approach to Unification and Quantum Gravity

2018 ◽  
Author(s):  
Michael Silberstein ◽  
W.M. Stuckey ◽  
Timothy McDevitt
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Quantum Gravity ◽  
Particle Physics ◽  
Lattice Gauge Theory ◽  
Galactic Rotation ◽  
Microwave Background ◽  
Angular Power Spectrum ◽  
Lattice Gauge ◽  
Main Thread

The main thread of chapter 6 prompts the need for quantum gravity (QG) and introduces the RBW approach to QG, unification in particle physics, dark matter, and dark energy. The details of RBW’s modified Regge calculus and modified lattice gauge theory approaches are conveyed conceptually in the main thread. The RBW fits of galactic rotation curves, galactic cluster mass profiles, the angular power spectrum of the cosmic microwave background, and the Union2.1 supernova data associated with dark matter and dark energy are in Foundational Physics for Chapter 6. In Philosophy of Physics for Chapter 6, RBW’s taxonomic location with respect to other discrete approaches to QG is detailed and it is argued that the search for QG is stymied by the dynamical paradigm across the board. Further, it is maintained that an adynamical global constraint as the basis for QG in the block universe provides a self-vindicating unification of physics.

scholarly journals Unified Dark Matter Scalar Field Models

2010 ◽  
Vol 2010 ◽  
pp. 1-29 ◽  
Author(s):  
Daniele Bertacca ◽  
Nicola Bartolo ◽  
Sabino Matarrese
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Galactic Halo ◽  
Kinetic Term ◽  
Spherically Symmetric ◽  
Rotation Curves ◽  
Spherically Symmetric Solutions ◽  
Scalar Field Models ◽  
Unified Description

We analyze and review cosmological models in which the dynamics of a single scalar field accounts for a unified description of the Dark Matter and Dark Energy sectors, dubbed Unified Dark Matter (UDM) models. In this framework, we consider the general Lagrangian of -essence, which allows to find solutions around which the scalar field describes the desired mixture of Dark Matter and Dark Energy. We also discuss static and spherically symmetric solutions of Einstein's equations for a scalar field with noncanonical kinetic term, in connection with galactic halo rotation curves.

scholarly journals Origin and evolution of structure and nucleosynthesis for galaxies in the local group

2014 ◽  
Vol 29 (14) ◽  
pp. 1430012 ◽  
Author(s):  
G. J. Mathews ◽  
A. Snedden ◽  
L. A. Phillips ◽  
I.-S. Suh ◽  
J. Coughlin ◽  
...  
Keyword(s):  
Dark Matter ◽  
Local Group ◽  
Galactic Halo ◽  
Galactic Plane ◽  
Dwarf Galaxies ◽  
Gravitational Interaction ◽  
Galactic Halos ◽  
Origin And Evolution ◽  
Spiral Density Waves ◽  
Streaming Flows

The Milky Way is the product of a complex evolution of generations of mergers, collapse, star formation, supernova and collisional heating, radiative and collisional cooling, and ejected nucleosynthesis. Moreover, all of this occurs in the context of the cosmic expansion, the formation of cosmic filaments, dark matter halos, spiral density waves, and emerging dark energy. In this review we summarize observational evidence and discuss recent calculations concerning the formation, evolution nucleosynthesis in the galaxies of the Local Group (LG). In particular, we will briefly summarize observations and simulations for the dwarf galaxies and the two large spirals of the LG. We discuss how galactic halos form within the dark matter filaments that define a super-galactic plane. Gravitational interaction along this structure leads to streaming flows toward the two dominant galaxies in the cluster. These simulations and observations also suggest that a significant fraction of the Galactic halo formed as at large distances and then arrived later along these streaming flows. We also consider the insight provided by observations and simulations of nucleosynthesis both within the galactic halo and dwarf galaxies in the LG.

scholarly journals Scalar-field theory of dark matter

2014 ◽  
Vol 29 (13) ◽  
pp. 1450074 ◽  
Author(s):  
Kerson Huang ◽  
Chi Xiong ◽  
Xiaofei Zhao
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Gordon Equation ◽  
Galactic Halo ◽  
Galactic Rotation ◽  
Klein Gordon ◽  
External Sources ◽  
Galaxy Collisions ◽  
The Universe ◽  
Klein Gordon Equation

We develop a theory of dark matter based on a previously proposed picture, in which a complex vacuum scalar field makes the universe a superfluid, with the energy density of the superfluid giving rise to dark energy, and variations from vacuum density giving rise to dark matter. We formulate a nonlinear Klein–Gordon equation to describe the superfluid, treating galaxies as external sources. We study the response of the superfluid to the galaxies, in particular, the emergence of the dark-matter galactic halo, contortions during galaxy collisions and the creation of vortices due to galactic rotation.

scholarly journals What laboratory experiments can teach us about cosmology: A chameleon example

2019 ◽  
Vol 219 ◽  
pp. 05001
Author(s):  
Clare Burrage
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Laboratory Experiments ◽  
New Physics ◽  
Cosmological Distance ◽  
Linear Behavior ◽  
Modify Gravity ◽  
Experimental Community ◽  
Shed Light ◽  
Theoretical Developments

Laboratory experiments can shed light on theories of new physics introduced in order to explain cosmological mysteries, including the nature of dark energy and dark matter. In this article I will focus on one particular example of this, the chameleon model. The chameleon is an example of a theory which could modify gravity on cosmological distance scales, but its non-linear behavior means that it can also be tested with suitably designed laboratory experiments. The aim of this overview is to present recent theoretical developments to the experimental community.

Alternative Gravitational Theories

2020 ◽  
pp. 146-176
Author(s):  
John W. Moffat
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Modified Gravity ◽  
Gravitational Theory ◽  
Alternative Theory ◽  
Gravitational Theories ◽  
Accelerating Expansion ◽  
Modified Gravity Theories ◽  
Expansion Of The Universe ◽  
Dynamics Of Galaxies

There have been many proposed modifications of gravitational theory, beginning with Einstein’s general relativity, modifying Newtonian gravity, and Weyl’s attempt at unifying gravity and electromagnetism. The standard model of cosmology, the Lambda CDM model, requires dark matter and dark energy to fit experimental data. There is a lack of direct evidence for dark matter and dark energy. An alternative theory called modified gravity (MOG) seeks to fit the observational data for the dynamics of galaxies and clusters of galaxies without dark matter. The MOG gravitational theory has a solution for a black hole that modifies the Schwarzschild and Kerr solutions, and can be tested using the data collected on supermassive black holes by the Event Horizon Telescope. There are many modified gravity theories proposed to explain the accelerating expansion of the universe, generally ascribed to dark energy. However, Einstein’s cosmological constant is the simplest explanation for the accelerating expansion.

scholarly journals Gravitational lensing study of cold dark matter-led galactic halo

2021 ◽  
pp. 2150089
Author(s):  
Samrat Ghosh ◽  
Arunava Bhadra ◽  
Amitabha Mukhopadhyay
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Cold Dark Matter ◽  
Galactic Halo ◽  
Gravitational Lens ◽  
Galactic Rotation ◽  
Spacetime Geometry ◽  
The Galaxy ◽  
Galactic Rotation Curve ◽  
Fisher Relation

In this work, the spacetime geometry of the halo region in spiral galaxies is obtained considering the observed flat galactic rotation curve feature, invoking the Tully–Fisher relation and assuming the presence of cold dark matter in the galaxy. The gravitational lensing analysis is performed treating the so-obtained spacetime as a gravitational lens. It is found that the aforementioned spacetime as the gravitational lens can consistently explain the galaxy–galaxy weak gravitational lensing observations and the lensing observations of the well-known Abell 370 and Abell 2390 galaxy clusters.

Cosmological constant

2018 ◽  
Author(s):  
Michael Kachelriess
Keyword(s):  
Dark Energy ◽  
Cosmological Constant ◽  
Accelerated Expansion ◽  
Vacuum Fluctuations ◽  
Present Epoch ◽  
Modify Gravity ◽  
Expansion Of The Universe ◽  
The Universe

The contribution of vacuum fluctuations to the cosmological constant is reconsidered studying the dependence on the used regularisation scheme. Then alternative explanations for the observed accelerated expansion of the universe in the present epoch are introduced which either modify gravity or add a new component of matter, dubbed dark energy. The chapter closes with some comments on attempts to quantise gravity.

Sign in / Sign up

Export Citation Format

Share Document