Pub Date : 2023-05-05DOI: 10.1142/s0218271823500542
J. E. Rosales Quintero
{"title":"A MacDowell-Mansouri type formulation for Conformally Flat Einstein manifolds","authors":"J. E. Rosales Quintero","doi":"10.1142/s0218271823500542","DOIUrl":"https://doi.org/10.1142/s0218271823500542","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46937715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-05DOI: 10.1142/s0218271823500554
F. Maqsood, Z. Yousaf, M. Z. Bhatti, Sana Rehman
{"title":"Analysis of Isotropic Pressure Condition in Chameleonic Brans-Dicke Gravity","authors":"F. Maqsood, Z. Yousaf, M. Z. Bhatti, Sana Rehman","doi":"10.1142/s0218271823500554","DOIUrl":"https://doi.org/10.1142/s0218271823500554","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48084318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-02DOI: 10.1142/S0218271823500530
Albert Munyeshyaka, J. Ntahompagaze, T. Mutabazi, Manasse R. Mbonye
The consideration of a 1 + 3 covariant approach to cold dark matter universe with no shear cosmological dust model with irrotational flows is developed in the context of f (G) gravity theory in the present study. This approach reveals the existence of integrability conditions which do not appear in non-covariant treatments. We constructed the integrability conditions in modified Gauss-Bonnet f (G) gravity basing on the constraints and propagation equations. These integrability conditions reveal the linearized silent nature of quasi-Newtonian models in f (G) gravity. Finally, the linear equations for the overdensity and velocity perturbations of the quasi-Newtonian space-time were constructed in the context of modified f (G) gravity. The application of harmonic decomposition and redshift transformation techniques to explore the behaviour of the overdensity and velocity perturbations using f (G) model were made. On the other hand we applied the quasi-static approximation to study the approximated solutions on small scales which helps to get both analytical and numerical results of the perturbation equations. The analysis of the energy overdensity and velocity perturbations for both short and long wavelength modes in a dust-Gauss-Bonnet fluids were done and we see that both energy overdensity and velocity perturbations decay with redshift for both modes. In the limits to {Lambda}CDM , it means f (G) = G the considered f (G) model results coincide with {Lambda}CDM .
{"title":"On 1 + 3 covariant perturbations of the quasi-Newtonian space-time in modified Gauss-Bonnet gravity","authors":"Albert Munyeshyaka, J. Ntahompagaze, T. Mutabazi, Manasse R. Mbonye","doi":"10.1142/S0218271823500530","DOIUrl":"https://doi.org/10.1142/S0218271823500530","url":null,"abstract":"The consideration of a 1 + 3 covariant approach to cold dark matter universe with no shear cosmological dust model with irrotational flows is developed in the context of f (G) gravity theory in the present study. This approach reveals the existence of integrability conditions which do not appear in non-covariant treatments. We constructed the integrability conditions in modified Gauss-Bonnet f (G) gravity basing on the constraints and propagation equations. These integrability conditions reveal the linearized silent nature of quasi-Newtonian models in f (G) gravity. Finally, the linear equations for the overdensity and velocity perturbations of the quasi-Newtonian space-time were constructed in the context of modified f (G) gravity. The application of harmonic decomposition and redshift transformation techniques to explore the behaviour of the overdensity and velocity perturbations using f (G) model were made. On the other hand we applied the quasi-static approximation to study the approximated solutions on small scales which helps to get both analytical and numerical results of the perturbation equations. The analysis of the energy overdensity and velocity perturbations for both short and long wavelength modes in a dust-Gauss-Bonnet fluids were done and we see that both energy overdensity and velocity perturbations decay with redshift for both modes. In the limits to {Lambda}CDM , it means f (G) = G the considered f (G) model results coincide with {Lambda}CDM .","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47410944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-28DOI: 10.1142/s0218271823500517
Sijo Joseph
{"title":"Quantum Origins of Scalar Gravitational Waves: Exploring the Conformal Factor in Scalar-Tensor Theory of Gravity","authors":"Sijo Joseph","doi":"10.1142/s0218271823500517","DOIUrl":"https://doi.org/10.1142/s0218271823500517","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45895338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-17DOI: 10.1142/s0218271823410018
M. Dunajski
In this paper, I discuss the impact of the positive cosmological constant on the interplay between the equivalence principle in general relativity, and the rules of quantum mechanics. At the nonrelativistic level, there is an ambiguity in the definition of a phase of a wave function measured by inertial and accelerating observes. This is the cosmological analogue of the Penrose effect, which can also be seen as a nonrelativistic limit of the Unruh effect. The symmetries of the associated Schrödinger equation are generated by the Newton–Hooke algebra, which arises from a nonrelativistic limit of a cosmological twistor space.
{"title":"Equivalence principle, de-Sitter space, and cosmological twistors","authors":"M. Dunajski","doi":"10.1142/s0218271823410018","DOIUrl":"https://doi.org/10.1142/s0218271823410018","url":null,"abstract":"In this paper, I discuss the impact of the positive cosmological constant on the interplay between the equivalence principle in general relativity, and the rules of quantum mechanics. At the nonrelativistic level, there is an ambiguity in the definition of a phase of a wave function measured by inertial and accelerating observes. This is the cosmological analogue of the Penrose effect, which can also be seen as a nonrelativistic limit of the Unruh effect. The symmetries of the associated Schrödinger equation are generated by the Newton–Hooke algebra, which arises from a nonrelativistic limit of a cosmological twistor space.","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44291050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-13DOI: 10.1142/s0218271823500451
jing-jing liu, Dong-Mei Liu, Qiu-He Peng
{"title":"New limit on magnetic monopole flux from catalysis of nucleon decay in white dwarfs","authors":"jing-jing liu, Dong-Mei Liu, Qiu-He Peng","doi":"10.1142/s0218271823500451","DOIUrl":"https://doi.org/10.1142/s0218271823500451","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43606792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-13DOI: 10.1142/s0218271823500475
S. Marongwe
{"title":"Horizon Scale Tests of Quantum Gravity using the Event Horizon Telescope observations","authors":"S. Marongwe","doi":"10.1142/s0218271823500475","DOIUrl":"https://doi.org/10.1142/s0218271823500475","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43526062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-13DOI: 10.1142/s021827182350044x
A. Hermanto, Yusmantoro, Romy H. S. Budhi
{"title":"Chameleonic Dark Matter and Reheating Constraints in a Logarithmic f(R)Gravity","authors":"A. Hermanto, Yusmantoro, Romy H. S. Budhi","doi":"10.1142/s021827182350044x","DOIUrl":"https://doi.org/10.1142/s021827182350044x","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48128821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-13DOI: 10.1142/s0218271823500487
H. Barman, M. Moussa, H. Shababi, Anisur Rahaman
{"title":"Thermodynamical character and the radiation process of the thin accretion disk of minimum measurable length inspired regular black hole","authors":"H. Barman, M. Moussa, H. Shababi, Anisur Rahaman","doi":"10.1142/s0218271823500487","DOIUrl":"https://doi.org/10.1142/s0218271823500487","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44990010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-07DOI: 10.1142/S0218271823500311
Gary Nash
Modified General Relativity (MGR) is the natural extension of General Relativity (GR). MGR explicitly uses the smooth regular line element vector field [Formula: see text], which exists in all Lorentzian spacetimes, to construct a connection-independent symmetric tensor that represents the energy–momentum of the gravitational field. It solves the problem of the nonlocalization of gravitational energy–momentum in GR, preserves the ontology of the Einstein equation, and maintains the equivalence principle. The line element field provides MGR with the extra freedom required to describe dark energy and dark matter. An extended Schwarzschild solution for the matter-free Einstein equation of MGR is developed, from which the Tully–Fisher relation is derived, and the gravitational energy density is calculated. The mass of the invisible matter halo of galaxy NGC 3198 calculated with MGR is identical to the result obtained from GR using a dark matter profile. Although dark matter in MGR is described geometrically, it has an equivalent representation as a particle with the property of a vector boson or a pair of fermions; the geometry of spacetime and the quantum nature of matter are linked together by the unit line element covectors that belong to both the Lorentzian metric and the spin-1 Klein–Gordon wave equation. The three classic tests of GR provide a comparison of the theories in the solar system and several parts of the cosmos. MGR provides the flexibility to describe inflation after the Big Bang and galactic anisotropies.
{"title":"Modified general relativity and dark matter","authors":"Gary Nash","doi":"10.1142/S0218271823500311","DOIUrl":"https://doi.org/10.1142/S0218271823500311","url":null,"abstract":"Modified General Relativity (MGR) is the natural extension of General Relativity (GR). MGR explicitly uses the smooth regular line element vector field [Formula: see text], which exists in all Lorentzian spacetimes, to construct a connection-independent symmetric tensor that represents the energy–momentum of the gravitational field. It solves the problem of the nonlocalization of gravitational energy–momentum in GR, preserves the ontology of the Einstein equation, and maintains the equivalence principle. The line element field provides MGR with the extra freedom required to describe dark energy and dark matter. An extended Schwarzschild solution for the matter-free Einstein equation of MGR is developed, from which the Tully–Fisher relation is derived, and the gravitational energy density is calculated. The mass of the invisible matter halo of galaxy NGC 3198 calculated with MGR is identical to the result obtained from GR using a dark matter profile. Although dark matter in MGR is described geometrically, it has an equivalent representation as a particle with the property of a vector boson or a pair of fermions; the geometry of spacetime and the quantum nature of matter are linked together by the unit line element covectors that belong to both the Lorentzian metric and the spin-1 Klein–Gordon wave equation. The three classic tests of GR provide a comparison of the theories in the solar system and several parts of the cosmos. MGR provides the flexibility to describe inflation after the Big Bang and galactic anisotropies.","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2023-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46241932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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