Modified Gauge Invariant Einstein-Maxwell Gravity and Stability of Spherical Perfect Fluid Stars with Magnetic Monopoles
As an alternative gravity model, we consider an extended Einstein-Maxwell gravity containing a gauge invariance property. An extension is assumed to be an addition of a directional coupling between spatial electromagnetic fields with the Ricci tensor. We will see importance of the additional term in...
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| Format: | Article |
| Language: | English |
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Damghan university
2024-01-01
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| Series: | Iranian Journal of Astronomy and Astrophysics |
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| Online Access: | https://ijaa.du.ac.ir/article_390_3043c49c5f7689f75b3568e2b216959e.pdf |
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| _version_ | 1841545161934372864 |
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| author | Hossein Ghaffarnejad Leyla Naderi |
| author_facet | Hossein Ghaffarnejad Leyla Naderi |
| author_sort | Hossein Ghaffarnejad |
| collection | DOAJ |
| description | As an alternative gravity model, we consider an extended Einstein-Maxwell gravity containing a gauge invariance property. An extension is assumed to be an addition of a directional coupling between spatial electromagnetic fields with the Ricci tensor. We will see importance of the additional term in making a compact stellar object and the value of its radius. As an application of this model we substitute ansatz of the magnetic field of a hypothetical magnetic monopole which has just time independent radial component and for matter part we assume a perfect fluid stress tensor. To obtain spherically symmetric internal metric of the perfect fluid stellar compact object we solve the Tolman-Oppenheimer-Volkoff equation with a polytropic form of equation of state as p(ρ) = aρ2. Using dynamical system approach we study stability of the solutions for which arrow diagrams show saddle (quasi stable) for a < 0 (dark stars) and sink (stable) for a > 0 (normal visible stars). We check also the energy conditions, speed of sound and Harrison-Zeldovich-Novikov static stability criterion for obtained solution and confirm that they make stable state. |
| format | Article |
| id | doaj-art-dfe2b2db6b844d0382acf94db6d3854f |
| institution | Kabale University |
| issn | 2322-4924 2383-403X |
| language | English |
| publishDate | 2024-01-01 |
| publisher | Damghan university |
| record_format | Article |
| series | Iranian Journal of Astronomy and Astrophysics |
| spelling | doaj-art-dfe2b2db6b844d0382acf94db6d3854f2025-01-12T10:03:52ZengDamghan universityIranian Journal of Astronomy and Astrophysics2322-49242383-403X2024-01-0110436538310.22128/ijaa.2024.759.1175390Modified Gauge Invariant Einstein-Maxwell Gravity and Stability of Spherical Perfect Fluid Stars with Magnetic MonopolesHossein Ghaffarnejad0Leyla Naderi1Faculty of Physics, Semnan Universiy, Semnan, Iran, 35131-19111Faculty of Physics, Semnan Universiy, Semnan, Iran, 35131-19111As an alternative gravity model, we consider an extended Einstein-Maxwell gravity containing a gauge invariance property. An extension is assumed to be an addition of a directional coupling between spatial electromagnetic fields with the Ricci tensor. We will see importance of the additional term in making a compact stellar object and the value of its radius. As an application of this model we substitute ansatz of the magnetic field of a hypothetical magnetic monopole which has just time independent radial component and for matter part we assume a perfect fluid stress tensor. To obtain spherically symmetric internal metric of the perfect fluid stellar compact object we solve the Tolman-Oppenheimer-Volkoff equation with a polytropic form of equation of state as p(ρ) = aρ2. Using dynamical system approach we study stability of the solutions for which arrow diagrams show saddle (quasi stable) for a < 0 (dark stars) and sink (stable) for a > 0 (normal visible stars). We check also the energy conditions, speed of sound and Harrison-Zeldovich-Novikov static stability criterion for obtained solution and confirm that they make stable state.https://ijaa.du.ac.ir/article_390_3043c49c5f7689f75b3568e2b216959e.pdfmagnetic monopolesstabilitystarsdynamical systemspherical |
| spellingShingle | Hossein Ghaffarnejad Leyla Naderi Modified Gauge Invariant Einstein-Maxwell Gravity and Stability of Spherical Perfect Fluid Stars with Magnetic Monopoles Iranian Journal of Astronomy and Astrophysics magnetic monopoles stability stars dynamical system spherical |
| title | Modified Gauge Invariant Einstein-Maxwell Gravity and Stability of Spherical Perfect Fluid Stars with Magnetic Monopoles |
| title_full | Modified Gauge Invariant Einstein-Maxwell Gravity and Stability of Spherical Perfect Fluid Stars with Magnetic Monopoles |
| title_fullStr | Modified Gauge Invariant Einstein-Maxwell Gravity and Stability of Spherical Perfect Fluid Stars with Magnetic Monopoles |
| title_full_unstemmed | Modified Gauge Invariant Einstein-Maxwell Gravity and Stability of Spherical Perfect Fluid Stars with Magnetic Monopoles |
| title_short | Modified Gauge Invariant Einstein-Maxwell Gravity and Stability of Spherical Perfect Fluid Stars with Magnetic Monopoles |
| title_sort | modified gauge invariant einstein maxwell gravity and stability of spherical perfect fluid stars with magnetic monopoles |
| topic | magnetic monopoles stability stars dynamical system spherical |
| url | https://ijaa.du.ac.ir/article_390_3043c49c5f7689f75b3568e2b216959e.pdf |
| work_keys_str_mv | AT hosseinghaffarnejad modifiedgaugeinvarianteinsteinmaxwellgravityandstabilityofsphericalperfectfluidstarswithmagneticmonopoles AT leylanaderi modifiedgaugeinvarianteinsteinmaxwellgravityandstabilityofsphericalperfectfluidstarswithmagneticmonopoles |