Special Issue "Relativistic Cosmology, Numerical Analysis, General Relativity and Modified Gravity Theories"

A special issue of Galaxies (ISSN 2075-4434).

Deadline for manuscript submissions: 31 July 2022.

Special Issue Editors

Dr. Zeeshan Yousaf
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Guest Editor
Department of Mathematics, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan
Interests: mathematical physics; geometry; nonlinear analysis; differential equations; gravitation
Special Issues and Collections in MDPI journals
Dr. M. Z. Bhatti
E-Mail Website
Guest Editor
Department of Mathematics, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan
Interests: geometry; nonlinear analysis; theoretical and mathematical physics; relativistic astrophysics; cosmology
Special Issues and Collections in MDPI journals
Dr. Tayyaba Akram
E-Mail Website
Guest Editor
School of Mathematical Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia
Interests: numerical analysis; fractional calculus; numerical simulations; stability analysis; convergence analysis

Special Issue Information

Dear Colleagues,

This Special Issue welcomes original research articles that focus on the analysis of astrophysical objects in the context of Extended Gravity Theories. We also welcome the paper related to numerical simulations of linear and non-linear dynamical systems. We are hoping to attract studies regarding the possible attainment of high masses of neutron stars and white dwarfs from the Extended Gravity Theories perspective. Moreover, the question of whether it is possible to obtain nonexotic matter wormhole solutions in these theories is expected to be addressed. The physical consequences of studying black holes, strange stars, and gravastars in Extended Gravity Theories are also welcome. The purpose of this special issue is to compile original findings with an emphasis on numerical and theoretical challenges in dynamical systems. Review articles on the current state of the art are also invited.

Traditional formulations or more recent methods based on compartmental models, dynamic networking systems, multi-scale problems, linear and nonlinear differential equations, fractional differential equations and Hamiltonian dynamic evolutions are all welcome. We also expect to receive review articles describing the current state-of-the-art within this broad subject. Potential topics include but are not limited to the following:

 

Astrophysics and Astroparticle Physics

Astronomical observations; cosmological implications of the God particle; dark matter astrophysics; dark energy; electromagnetic process and properties; fundamental aspects of astrophysics; high-energy astrophysics/astroparticle; relativistic stars, structure, stability and oscillation—other topics.

 

Cosmology

Cosmic acceleration; cosmic microwave background radiation; inhomogeneous exact cosmologies; large scale structures; mathematical and relativistic aspects of cosmology; observational cosmology including the Hubble constant, distance scale, cosmological constant, early universe; theoretical cosmology—other topics.

 

Compact Objects

Black holes, mergers and accretion disks; galaxy evolution; measurements common to several branches of physics and astronomy; neutron stars; self-gravitating systems; strong gravitational lensing—other topics.

 

General Relativity and Modified Gravity Theories

Alternative theories of gravity; classical general relativity; numerical studies of critical behavior, singularities and cosmic censorship; strong-field tests of general relativity—other topics.

 

Non-linear Analysis

Non-linear analysis in mathematics, physics, biologychemistryengineering, economicshistory, and medicine; dynamical systems; linear dynamic system; nonlinear dynamic system; theoretical challenges in differetial calculus; numerical methods; fractional differential equations.

 

Dr. Zeeshan Yousaf
Dr. Kazuharu Bamba
Dr. M. Z. Bhatti
Dr. Tayyaba Akram
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Galaxies is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • astrophysics and astroparticle physics
  • cosmology
  • compact objects
  • general relativity and modified gravity theories

Published Papers (2 papers)

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Research

Article
The Effects of Inertial Forces on the Dynamics of Disk Galaxies
Galaxies 2021, 9(2), 34; https://doi.org/10.3390/galaxies9020034 - 13 May 2021
Viewed by 672
Abstract
When dealing with galactic dynamics, or more specifically, with galactic rotation curves, one basic assumption is always taken: the frame of reference relative to which the rotational velocities are given is assumed to be inertial. In other words, fictitious forces are assumed to [...] Read more.
When dealing with galactic dynamics, or more specifically, with galactic rotation curves, one basic assumption is always taken: the frame of reference relative to which the rotational velocities are given is assumed to be inertial. In other words, fictitious forces are assumed to vanish relative to the observational frame of a given galaxy. It might be interesting, however, to explore the outcomes of dropping that assumption; that is, to search for signatures of non-inertial behavior in the observed data. In this work, we show that the very discrepancy in galaxy rotation curves could be attributed to non-inertial effects. We derive a model for spiral galaxies that takes into account the possible influence of fictitious forces and find that the additional terms in the new model, due to fictitious forces, closely resemble dark halo profiles. Following this result, we apply the new model to a wide sample of galaxies, spanning a large range of luminosities and radii. It turns out that the new model accurately reproduces the structures of the rotation curves and provides very good fittings to the data. Full article
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Article
Magnetized Particle Motion in γ-Spacetime in a Magnetic Field
Galaxies 2020, 8(4), 76; https://doi.org/10.3390/galaxies8040076 - 29 Oct 2020
Cited by 5 | Viewed by 811
Abstract
In the present work we explored the dynamics of magnetized particles around the compact object in γ-spacetime in the presence of an external asymptotically-uniform magnetic field. The analysis of the circular orbits of magnetized particles around the compact object in the spacetime of a γ-object immersed in the external magnetic field has shown that the area of stable circular orbits of magnetized particles increases with the increase of γ-parameter. We have also investigated the acceleration of the magnetized particles near the γ-object and shown that the center-of-mass energy of colliding magnetized particles increases with the increase of γ-parameter. Finally, we have applied the obtained results to the astrophysical scenario and shown that the values of γ-parameter in the range of γ(0.5,1) can mimic the spin of Kerr black hole up to a0.85, while the magnetic interaction can mimic the γ-parameter at γ(0.8,1) and spin of a Kerr black hole up to a0.3. Full article
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