arXiv subjects

Elham Ghasemi

Publications and source records attributed to Elham Ghasemi.

4 recordsLinked to original sources

arXiv2023

Central AdS Generalized Ay{ó}n-Beato-Garc{\'ı}a Black Holes and Joule-Thomson Expansion

In this paper, the Joule-Thomson (JT) adiabatic expansion is investigated for generalized Ayon-Beato-Garcia (ABG) regular black hole. It has a magnetic charge which makes central region of the black hole metric to be AdS spacetime and so become non singular. Thus we not need to use an additional cosmological parameter coming from ADS/CFT correspondence for production of pressure coordinate in the black hole equation of state. Form this point of view our work is a new approach versus to conventional methods which are addressed in the references of this paper. However we will see important behavior of parameters of this modified ABG black hole on possibility of being of JT adiabatic expansion. This black hole is characterized by five parameters including mass $m$, magnetic charge $q$, and three other parameters related to form of used nonlinear electromagnetic interaction fields. Inversion points are in fact a particular T-P curve at constant enthalpy and it separates cooling and heating phase of the modified AdS ABG black hole.

gr-qc↗

arXiv2023

Thermodynamic phase transition of Anti-de Sitter Reissner-Nordstr\"{o}m black holes with exotic Einstein-Maxwell gravities

To consider the inevitable cosmic magnetic effects instead of the unknown dark sector of matter/energy on the inflation phase of the expanding universe some authors have proposed several extended exotic Einstein-Maxwell gravities which are addressed in this work. Some of these exotic models include directional interaction terms between the electromagnetic vector field and the metric tensor field. We use one of them to investigate the physical effects of interaction terms on the thermodynamic behavior of the modified Reissner-Nordstrom (RN) black hole. We use the perturbation series method to find analytic solutions of the field equations because of the non-linearity of the field equations which cause they do not have analytic closed form solutions. We investigate possibility of the Hawking-Page and the small/large black hole phase transition and also, effects of the interaction part of the model on possibility of the coexistence of the several phases of the perturbed AdS RN black hole under consideration.

gr-qc↗

arXiv2023

Thermodynamic Phase Transition of Generalized Ayon-Beato Garcia Black Holes

In this work we study thermodynamics of generalized Ayon-Beato and Garcia (ABG) black hole metric which contains three parameters named as mass $m$, magnetic charge $q$ and dimensionless coupling constant of nonlinear electrodynamics interacting field $γ$. We showed that central regions of this black hole behaves as dS(AdS) vacuum space by setting $q<2m (q>2m)$ and in the case $q=2m$ reaches to a flat Minkowski space. In the large distances this black hole behaves as a Reissner-Nordstrom BH. However important role of the charge q is appeared in produce of a formal variable cosmological parameter which will support pressure coordinate in the thermodynamic perspective of this black hole in our setup. We should be point that this formal variable cosmological parameter is different with cosmological constant which comes from AdS/CFT correspondence and it is effective at large distances as AdS space pressure. In our setup the assumed pressure is originated from internal material of the black hole say q and m here. By calculating the Hawking temperature of this black hole we obtain equation of state. Then we plotted isothermal P-v curves and heat capacity at constant pressure. They show that the system participates in the small to large phase transition of the black hole or the Hawking-Page phase transition which is similar to the Van der Waals phase transition in the ordinary thermodynamics systems . In fact in the Hawking-Page phase transition disequilibrium evaporating generalized ABG black hole reaches to a vacuum AdS space finally.

hep-th↗

arXiv2022

Magnetic charge effects on thermodynamic phase transition of modified Anti de Sitter Ayón-Beato-García Black Holes with five parameters

In this letter we choose generalized Ayon Beato Gracia (ABG) magnetic charged black hole with five parameters to investigate possibility of thermodynamic phase transition and coexistence of different gass/liquid/solid phases of this black hole. In fact this work is an extension of our recently work where ABG black hole with three parameters was used to seek the phase transition. In this work we obtain other physical values on the parameters with respect to our previous work where the phase transition is happened together with coexistence point of different phases in the phase space.

gr-qc↗