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- Title
Modified Gauge Invariant Einstein-Maxwell Gravity and Stability of Spherical Perfect Fluid Stars with Magnetic Monopoles.
- Authors
Ghaffarnejad, Hossein; Naderi, Leyla
- Abstract
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(?) = a?2. 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.
- Subjects
EINSTEIN-Maxwell equations; MAGNETIC monopoles; MAGNETIC field measurements; GAUGE invariance; POLYTROPIC processes
- Publication
Iranian Journal of Astronomy & Astrophysics, 2023, Vol 10, Issue 4, p365
- ISSN
2322-4924
- Publication type
Article
- DOI
10.22128/ijaa.2024.759.1175