TY - JOUR
ID - 390
TI - Modified Gauge Invariant Einstein-Maxwell Gravity and Stability of Spherical Perfect Fluid Stars with Magnetic Monopoles
JO - Iranian Journal of Astronomy and Astrophysics
JA - IJAA
LA - en
SN - 2322-4924
AU - Ghaffarnejad, Hossein
AU - Naderi, Leyla
AD - Faculty of Physics, Semnan Universiy, Semnan, Iran, 35131-19111
Y1 - 2024
PY - 2024
VL - 10
IS - 4
SP - 365
EP - 383
KW - Magnetic monopoles
KW - stability
KW - stars
KW - Dynamical system
KW - spherical
DO - 10.22128/ijaa.2024.759.1175
N2 - 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.
UR - https://ijaa.du.ac.ir/article_390.html
L1 - https://ijaa.du.ac.ir/article_390_3043c49c5f7689f75b3568e2b216959e.pdf
ER -