Dynamical systems approach to stellar modelling in f(G, B) gravity.
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| Title: | Dynamical systems approach to stellar modelling in f(G, B) gravity. |
|---|---|
| Authors: | Hansraj, Sudan1 (AUTHOR) hansrajs@ukzn.ac.za, Boehmer, Christian G.1,2 (AUTHOR) c.boehmer@ucl.ac.uk, Buthelezi, Ndumiso1 (AUTHOR) 215033901@stu.ukzn.ac.za |
| Source: | European Physical Journal C -- Particles & Fields. May2026, Vol. 86 Issue 5, p1-13. 13p. |
| Subjects: | Stellar dynamics, Stellar structure, Dynamical systems, Thermodynamic state variables, Differential equations, Mathematical decomposition, Spacetime |
| Abstract: | The novel proposal to invoke the split of the Ricci scalar into bulk and boundary terms in the gravitational action, opens up a new avenue of investigation into stellar dynamics. The Lagrangian contains functional forms of the bulk term while the boundary term do not contribute to the dynamics. The advantage of the proposition is that the stellar structure equations are up to order two, thus the theory is not haunted by ghosts. We obtain explicitly the defining equations for the thermodynamical variables and the geometry for the pure quadratic case, since the linear case amounts to general relativity. In trying to establish the vacuum geometry associated with the theory it turns out that two possible metrics emerge through the vanishing of the energy-momentum tensor. Next, we analyse the isotropy equation and make the observation that it is autonomous. It is rare that this happens in astrophysical modelling. This behaviour prompted the use of dynamical systems to understand the stability properties of fixed points or invariant submanifolds. It was necessary to choose a gauge in order to split the autonomous equation into a system from which we could plot a phase portrait and deduce the stability of solution trajectories. We find that the invariant submanifolds were generally stable with nearby paths approaching them. [ABSTRACT FROM AUTHOR] |
| Copyright of European Physical Journal C -- Particles & Fields is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
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| Header | DbId: egs DbLabel: Engineering Source An: 194633919 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Dynamical systems approach to stellar modelling in f(G, B) gravity. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Hansraj%2C+Sudan%22">Hansraj, Sudan</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> hansrajs@ukzn.ac.za</i><br /><searchLink fieldCode="AR" term="%22Boehmer%2C+Christian+G%2E%22">Boehmer, Christian G.</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<i> c.boehmer@ucl.ac.uk</i><br /><searchLink fieldCode="AR" term="%22Buthelezi%2C+Ndumiso%22">Buthelezi, Ndumiso</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> 215033901@stu.ukzn.ac.za</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22European+Physical+Journal+C+--+Particles+%26+Fields%22">European Physical Journal C -- Particles & Fields</searchLink>. May2026, Vol. 86 Issue 5, p1-13. 13p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Stellar+dynamics%22">Stellar dynamics</searchLink><br /><searchLink fieldCode="DE" term="%22Stellar+structure%22">Stellar structure</searchLink><br /><searchLink fieldCode="DE" term="%22Dynamical+systems%22">Dynamical systems</searchLink><br /><searchLink fieldCode="DE" term="%22Thermodynamic+state+variables%22">Thermodynamic state variables</searchLink><br /><searchLink fieldCode="DE" term="%22Differential+equations%22">Differential equations</searchLink><br /><searchLink fieldCode="DE" term="%22Mathematical+decomposition%22">Mathematical decomposition</searchLink><br /><searchLink fieldCode="DE" term="%22Spacetime%22">Spacetime</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: The novel proposal to invoke the split of the Ricci scalar into bulk and boundary terms in the gravitational action, opens up a new avenue of investigation into stellar dynamics. The Lagrangian contains functional forms of the bulk term while the boundary term do not contribute to the dynamics. The advantage of the proposition is that the stellar structure equations are up to order two, thus the theory is not haunted by ghosts. We obtain explicitly the defining equations for the thermodynamical variables and the geometry for the pure quadratic case, since the linear case amounts to general relativity. In trying to establish the vacuum geometry associated with the theory it turns out that two possible metrics emerge through the vanishing of the energy-momentum tensor. Next, we analyse the isotropy equation and make the observation that it is autonomous. It is rare that this happens in astrophysical modelling. This behaviour prompted the use of dynamical systems to understand the stability properties of fixed points or invariant submanifolds. It was necessary to choose a gauge in order to split the autonomous equation into a system from which we could plot a phase portrait and deduce the stability of solution trajectories. We find that the invariant submanifolds were generally stable with nearby paths approaching them. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of European Physical Journal C -- Particles & Fields is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1140/epjc/s10052-026-15749-2 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 13 StartPage: 1 Subjects: – SubjectFull: Stellar dynamics Type: general – SubjectFull: Stellar structure Type: general – SubjectFull: Dynamical systems Type: general – SubjectFull: Thermodynamic state variables Type: general – SubjectFull: Differential equations Type: general – SubjectFull: Mathematical decomposition Type: general – SubjectFull: Spacetime Type: general Titles: – TitleFull: Dynamical systems approach to stellar modelling in f(G, B) gravity. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Hansraj, Sudan – PersonEntity: Name: NameFull: Boehmer, Christian G. – PersonEntity: Name: NameFull: Buthelezi, Ndumiso IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 05 Text: May2026 Type: published Y: 2026 Identifiers: – Type: issn-print Value: 14346044 Numbering: – Type: volume Value: 86 – Type: issue Value: 5 Titles: – TitleFull: European Physical Journal C -- Particles & Fields Type: main |
| ResultId | 1 |
